Multidisciplinary management of acute cholecystitis during the COVID-19 pandemic

The coronavirus disease 2019 pandemic had a major impact on most medical services. Our aim was to assess the outcome of acute cholecystitis during the nationwide lockdown period. All patients admitted to our emergency department for AC were analysed. Patient characteristics, performance status, AC severity, treatment modality and outcome of AC were assessed during the lockdown period (Period II: 1 April 2020-30 November 2021) and compared to a historical control period (Period I: 1 May 2017-31 December 2018). AC admissions increased by 72.8% in Period II. Patients were younger (70 vs. 74 years, p = 0.017) and greater in number in the CCI 1 group (20.4% vs. 11.2%, p = 0.043) in Period II. The unplanned readmission rate (6.3 vs. 0%, p = 0.004) and the gallbladder perforation (GP) rate was higher (18.0 vs. 7.3%, p = 0.006) in Period II. Percutaneous transhepatic gallbladder drainage (PTGBD) was more frequent (24.1 vs. 12.8%, p = 0.012) in Period II. In addition to a drop in patient age and CCI, a significant rise in the prevalence of acute cholecystitis, GP and unplanned readmissions was observed during the nationwide lockdown due to the COVID-19 pandemic. PTGBD was more frequent during this period, whereas successful conservative treatment was less frequent.

Investigation of the Effect on the Albumin Binding Moiety for the Pharmacokinetic Properties of 68Ga-, 205/206Bi-, and 177Lu-Labeled NAPamide-Based Radiopharmaceuticals

Although radiolabeled alpha-melanocyte stimulating hormone-analogue NAPamide derivatives are valuable melanoma-specific diagnostic probes, their rapid elimination kinetics and high renal uptake may preclude them from being used in clinical settings. We aimed at improving the pharmacokinetics of radiolabeled DOTA-NAPamide compounds by incorporating a 4-(p-iodo-phenyl)-butanoic acid (IPB) into the molecules. Followed by 68Ga-, 205/206Bi-, and 177Lu-labelling, the radiopharmaceuticals ([68Ga]Ga-DOTA-IPB-NAPamide, [205/206Bi]Bi-DOTA-IPB-NAPamide, [177Lu]Lu-DOTA-IPB-NAPamide) were characterized in vitro. To test the imaging behavior of the IPB-containing probes, B16F10 tumor-bearing C57BL/6 mice were subjected to in vivo microPET/microSPECT/CT imaging and ex vivo biodistribution studies. All tracers were stable in vitro, with radiochemical purity exceeding 98%. The use of albumin-binding moiety lengthened the in vivo biological half-life of the IPB-carrying radiopharmaceuticals, resulting in elevated tumor accumulation. Both [68Ga]Ga-DOTA-IPB-NAPamide (5.06 ± 1.08 %ID/g) and [205/206Bi]Bi-DOTA-IPB-NAPamide (4.50 ± 0.98 %ID/g) exhibited higher B16F10 tumor concentrations than their matches without the albumin-binding residue ([68Ga]Ga-DOTA-NAPamide and [205/206Bi]Bi-DOTA-NAPamide: 1.18 ± 0.27 %ID/g and 3.14 ± 0.32; respectively), however; the large amounts of off-target radioactivity do not confirm the benefits of half-life extension for short-lived isotopes. Enhanced [177Lu]Lu-DOTA-IPB-NAPamide tumor uptake even 24 h post-injection proved the advantage of IPB-based prolonged circulation time regarding long-lived radionuclides, although the significant background noise must be addressed in this case as well.

[Pulmonary histiocytic sarcoma]

Histiocytic sarcoma is an uncommon hematological malignancy. Its occurrence in the lung is very rare. Due to the small number of cases and the clinical and pathological features of the disease, the diagnosis can be challenging. Its optimal treatment is not yet known, in locally confined cases - depending on the location and size - surgical removal is part of complex oncotherapy. We report the case of a 52-year-old man with a tumor of central localization in the left lung. Pulmonectomy was performed. Histology verified histiocytic sarcoma of the lung. An overview of clinical features of the entity is presented in connection with our case report. Orv Heti. 2023; 164(34): 1350-1357.

Gallium(III)- and Thallium(III)-Encapsulated Polyoxopalladates: Synthesis, Structure, Multinuclear NMR, and Biological Activity Studies

Three gallium(III)- and thallium(III)-containing polyoxopalladates (POPs) have been synthesized and structurally characterized in the solid state and in solution, namely, the phosphate-capped 12-palladate nanocubes [XPd12O8(PO4)8]13- (X = GaIII, GaPd12P8; X = TlIII, TlPd12P8) and the 23-palladate double-cube [Tl2IIIPd23P14O70(OH)2]20- (Tl2Pd23P14). The cuboid POPs, GaPd12P8 and TlPd12P8, are solution stable as verified by the respective 31P, 71Ga, and 205Tl nuclear magnetic resonance (NMR) spectra. Of prime interest, the spin-spin coupling schemes allowed for an intimate study of the solution behavior of the TlIII-containing POPs via a combination of 31P and 205Tl NMR, including the stoichiometry of the major fragments of Tl2Pd23P14. Moreover, biological studies demonstrated the antitumor and antiviral activity of GaPd12P8 and TlPd12P8, which were validated to be as efficient as cis-platinum against human melanoma and acute promyelocytic leukemia cells. Furthermore, GaPd12P8 and TlPd12P8 exerted inhibitory activity against two herpetic viruses, HSV-2 and HCMV, in a dose-response manner.

[Rare case of primary pulmonary myxoid sarcoma]

Mesenchymal tumors of the lungs are rare, mostly aggressive, with a high metastatic rate, representing only 0.013-1.1% of all pulmonary malignancies. Primary pulmonary myxoid sarcoma is an extremely rare type of lung sarcoma and stands as a separate entity in the 2015 WHO classification, characterized by EWSR1-CREB fusion gene. So far, 37 myxoid sarcoma cases have been reported. We offer an overview of the most important characteristics of pulmonary myxoid sarcoma and differential diagnosis, while reviewing the reported cases. We present the case of a 47-year-old patient with pulmonary myxoid sarcoma, who was diagnosed with a right central pulmonary mass, showing rapid endobronchial progression, complicated by empyema. EWSR1 gene translocation could not be detected. During chemotherapy, tumor progression occurred. Molecular genetic examinations revealed MET gene exon 14 skipping mutation, based on which tyrosine-kinase inhibitor treatment was administered. Pulmonary myxoid sarcoma can be classified as a nonvascular, spindle cell entity of mesenchymal tumors, with the characteristic EWSR1-CREB1 gene translocation. The male-female ratio is similar, with a slightly higher incidence in middle-aged women (1.5 : 1). Patients' average age is 44 years; with predilection in the right upper lobe (62%), or endobronchially (85%). Without specific symptoms, diagnosis is often cumbersome. Immunohistochemical methods, typical hystological image and molecular genetic tests confirm the diagnosis. Pulmonary myxoid sarcoma is a rare entity, without specific symptoms. In our case, myxoid sarcoma was complicated by empyema, which was drained. Because of advanced stage, surgical resection was not an option. Radical surgery offers the best results, in inoperable cases therapeutic recommendations for sarcomas are the guiding principles. Our case belongs to the rare group of myxoid sarcomas, where MET activating mutation was detected, making it eligible for targeted treatment. Orv Hetil. 2023; 164(27): 1077-1083.

Relationship between gadolinium-based MRI contrast agent consumption and anthropogenic gadolinium in the influent of a wastewater treatment plant

Gadolinium-based contrast agents (GBCAs) used in magnetic resonance imaging (MRI) are highly resistant in the environment. They pass through wastewater treatment plants (WWTPs) unhindered escaping degradation. Although GBCAs are subjects of intensive research, we recognized that a quantitative approach to the mass balance of gadolinium, based on known input and output data, is missing. The administered amount of Gd as GBCAs, the number of out- and inpatients and the concentration of rare earth elements (REEs) in wastewater were monitored for 45 days in a medium sized city (ca. 203,000 inhabitants) with two MRI centres. An advection-dispersion type model was established to describe the transport of Gd in the wastewater system. The model calculates with patient locality, excretion kinetics of Gd and the yield of wastewater. The estimated and measured daily amount of anthropogenic gadolinium released to the WWTP were compared. GBCAs (Omniscan and Dotarem) were administered to 1008 patients representing a total of 700 ± 1 g Gd. The amount of total Gd entering the WWTP was 531 ± 2 g, of which the anthropogenic contribution (i.e. GBCAs) was 261 ± 6 g (49 ± 1 % of the total Gd) during the sampling campaign. Local residents and inpatients should fully release Gd in the city, but outpatients only partially. Overall, 37 ± 1 % of the total administered Gd was recovered in the wastewater, so the remaining 63 ± 1 % of administered Gd is expected to be dispensed outside of the sewer system. Our approach enables to better understand the dispersion of GBCAs originated Gd in an urban environment.

A masszív haemothorax modern kezelése

Bevezetés és célkitűzés: A haemothorax szélsőségesen különböző etiológiájú és súlyosságú kórképek gyűjtőfogalma. Súlyos, masszív formája a leggyakrabban traumás eredetű, nemritkán iatrogén (intervenció, alvadást befolyásoló szerek), és elvétve ismeretlen. Az októl, a volumentől, a dinamikától függő, az adott beteghez illesztett és a módszerekhez való hozzáférés által megszabott kezelési stratégiák áttekintését tűztük ki célul. Módszerek: A Borsod-Abaúj-Zemplén Megyei Központi Kórház Mellkassebészeti Osztályán 2017. január 1. és 2021. december 31. között haemothorax miatt kezelt betegek adatait retrospektíven elemeztük. A kórház informatikai rendszerének adataiból a haemothorax okát, a választott kezelési módot, a kimenetelt (30 napos túlélés), az ápolási napok számát és a szövődményeket vizsgáltuk. Eredmények: 77 beteget kezeltünk haemothorax miatt, 57 férfit, 20 nőt. Betegeink átlagéletkora 53,4 (23–90, SD: 14,9) év volt. Műtétet 31 esetben végeztünk, 10 alkalommal történt reoperáció. Kombinált műtéti mellkasfali stabilizáció során végzett haematomaevakuáció 7 esetben vált szükségessé. Ápolási napok száma: 14 (2–79). 30 napos túlélés: 95%. Megbeszélés: Az elsődleges terápiás módszer a mellüregi drenázs. Az invazív radiológia biztosította digitális szubtrakciós angiográfiával (DSA) ez a módszer válogatott esetekben kiválthatja a műtéti feltárást. A minimálinvazivitást preferáló műtéti repertoárban a videotorakoszkópos (VATS-) műtét válik dominánssá. Következtetés: Ha a beteg általános állapota, a vérzés mértéke engedi, és elérhető a DSA, akkor a vérzéscsillapításra a mellkasi drenázst követően ez alkalmas módszer. Mellkasi drenázzsal dacoló esetben a VATS-haematomaevakuáció javallt. Többszörös bordatörés következtében kialakult instabil mellkast kísérő vérmell esetén a mellkasfali stabilizáció és a kiürítés kombinálandó. Osztályunkon egyre nagyobb arányban végzünk VATS-ot a haemothorax kezelésében. A minimálinvazív ellátás az arra alkalmas betegekben biztonságos, és a végeredményt tekintve a nyitott thoracotomia előnyös alternatívája. Orv Hetil. 2022; 163(43): 1727–1732.

A New Oxygen Containing Pyclen-Type Ligand as a Manganese(II) Binder for MRI and 52Mn PET Applications: Equilibrium, Kinetic, Relaxometric, Structural and Radiochemical Studies

A new pyclen-3,9-diacetate derivative ligand (H₂3,9-OPC2A) was synthesized possessing an etheric O-atom opposite to the pyridine ring, to improve the dissociation kinetics of its Mn(II) complex (pyclen = 3,6,9,15-tetraazabicyclo(9.3.1)pentadeca-1(15),11,13-triene). The new ligand is less basic than the N-containing analogue (H₂3,9-PC2A) due to the non-protonable O-atom. In spite of its lower basicity, the conditional stability of the [Mn(3,9-OPC2A)] (pMn = −log(Mn(II)), c_L = c_Mn(II) = 0.01 mM. pH = 7.4) remains unaffected (pMn = 8.69), compared to the [Mn(3,9-PC2A)] (pMn = 8.64). The [Mn(3,9-OPC2A)] possesses one water molecule, having a lower exchange rate with bulk solvents (k_ex²⁹⁸ = 5.3 ± 0.4 × 10⁷ s⁻¹) than [Mn(3,9-PC2A)] (k_ex²⁹⁸ = 1.26 × 10⁸ s⁻¹). These mild differences are rationalized by density-functional theory (DFT) calculations. The acid assisted dissociation of [Mn(3,9-OPC2A)] is considerably slower (k₁ = 2.81 ± 0.07 M⁻¹ s⁻¹) than that of the complexes of diacetates or bisamides of various 12-membered macrocycles and the parent H₂3,9-PC2A. The [Mn(3,9-OPC2A)] is inert in rat/human serum as confirmed by ⁵²Mn labeling (nM range), as well as by relaxometry (mM range). However, a 600-fold excess of EDTA (pH = 7.4) or a mixture of essential metal ions, propagated some transchelation/transmetalation in 7 days. The H₂3,9-OPC2A is labeled efficiently with ⁵²Mn at elevated temperatures, yet at 37 °C the parent H₂3,9-PC2A performs slightly better. Ultimately, the H₂3,9-OPC2A shows advantageous features for further ligand designs for bifunctional chelators.

Exploring Cyclic Aminopolycarboxylate Ligands for Sb(III) Complexation: PCTA and Its Derivatives as a Promising Solution

In recent years Auger electron emitters have been suggested as promising candidates for radiotherapy with no side effects in cancer treatment. In this work we report a detailed coordination chemistry study of [Sb(PCTA)] (PCTA: 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-3,6,9-triacetic acid), a macrocyclic aminopolycarboxylate-type complex of antimony(III), whose ¹¹⁹Sb isotope could be a suitable low-energy electron emitter for radiotherapy. The thermodynamic stability of the chelate obtained by pH-potentiometry and UV-vis spectrophotometry is high enough (log K_[Sb(PCTA)] = 23.2(1)) to prevent the hydrolysis of the metal ion near physiological pH. The formation of [Sb(PCTA)] is confirmed by NMR and electrospray ionization mass spectrometry measurements in solution; furthermore, the structure of [Sb(PCTA)]·NaCl·3H₂O and [Sb(PCTA)]·HCl·3H₂O is described by X-ray and density functional theory calculations. Consequently, the [Sb(PCTA)] is the first thermodynamically stable antimony(III) complex bearing polyamino-polycarboxylate macrocyclic platform. Our results demonstrate the potential of rigid (pyclen derivative) ligands as chelators for future applications of Sb(III) in a targeted radiotherapy based on the ¹¹⁹Sb isotope.

Towards 213Bi alpha-therapeutics and beyond: unravelling the foundations of efficient BiIII complexation by DOTP

Bi^III-DOTP complex is characterised by a fast formation kinetics, an outstanding thermodynamic stability and an impressive kinetic interness, making Bi^III-DOTP an optimal model for the development of targeted α-therapy (TAT) radiopharmaceuticals.

Complexation of Mn(II) by Rigid Pyclen Diacetates: Equilibrium, Kinetic, Relaxometric, Density Functional Theory, and Superoxide Dismutase Activity Studies

We report the Mn(II) complexes with two pyclen-based ligands (pyclen = 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene) functionalized with acetate pendant arms at either positions 3,6 (3,6-PC2A) or 3,9 (3,9-PC2A) of the macrocyclic fragment. The 3,6-PC2A ligand was synthesized in five steps from pyclen oxalate by protecting one of the secondary amine groups of pyclen using Alloc protecting chemistry. The complex with 3,9-PC2A is characterized by a higher thermodynamic stability [log K_MnL = 17.09(2)] than the 3,6-PC2A analogue [log K_MnL = 15.53(1); 0.15 M NaCl]. Both complexes contain a water molecule coordinated to the metal ion, which results in relatively high ¹H relaxivities (r_1p = 2.72 and 2.91 mM^-1 s^-1 for the complexes with 3,6-PC2A and 3,9-PC2A, respectively, at 25 °C and 0.49 T). The coordinated water molecule displays fast exchange kinetics with the bulk in both cases; the rates (k_ex²⁹⁸) are 140 × 10⁶ and 126 × 10⁶ s^-1 for [Mn(3,6-PC2A)(H₂O)] and [Mn(3,9-PC2A)(H₂O)], respectively. The two complexes were found to be remarkably inert with respect to their dissociation, with half-lives of 63 and 21 h, respectively, at pH = 7.4 in the presence of excess Cu(II). The r_1p values recorded in blood serum remain constant at least over a period of 120 h. Cyclic voltammetry experiments show irreversible oxidation features shifted to higher potentials with respect to [Mn(EDTA)(H₂O)]^2- (H₄EDTA = ethylenediaminetetraacetic acid) and [Mn(PhDTA)(H₂O)]^2- (H₄PhDTA = phenylenediamine-N,N,N',N'-tetraacetic acid), indicating that the PC2A complexes reported here have a lower tendency to stabilize Mn(III). The superoxide dismutase activity of the Mn(II) complexes was tested using the xanthine/xanthine oxidase/p-nitro blue tetrazolium chloride assay at pH = 7.8. The Mn(II) complexes of 3,6-PC2A and 3,9-PC2A are capable of assisting decomposition of the superoxide anion radical. The kinetic rate constant of the complex of 3,9-PC2A is smaller by 1 order of magnitude than that of 3,6-PC2A.

Shape and Size Tuning of BiIII-Centered Polyoxopalladates: High Resolution 209Bi NMR and 205/206Bi Radiolabeling for Potential Pharmaceutical Applications

We have discovered five bismuth(III)-containing polyoxopalladates (POPs) which were fully characterized by solution and solid-state physicochemical techniques: the cube-shaped [BiPd₁₂O₃₂(AsPh)₈]^5- (BiPd₁₂AsL), [BiPd₁₂O₃₂(AsC₆H₄N₃)₈]^5- (BiPd₁₂AsL_N), and [BiPd₁₂O₃₂(AsC₆H₄COO)₈]^13- (BiPd₁₂AsL_C) as well as the star-shaped [BiPd₁₅O₄₀(PO)₁₀H₆]^11- (BiPd₁₅P) and [BiPd₁₅O₄₀(PPh)₁₀]^7- (BiPd₁₅PL), respectively. The organically modified capping groups phenylarsonate, p-azidophenylarsonate, and p-carboxyphenylarsonate were chosen as the azido (-N₃) and carboxyl (-COOH) groups open up opportunities to covalently conjugate (via click reaction, amide coupling, etc.) with targeting vectors. The synthesis of p-azidophenylarsonate is reported here for the first time. The effects of the Bi^III template and the organoarsonate vs -posphonate capping groups on the resulting POP shape (cube vs star) are discussed. The ²⁰⁹Bi NMR (I = 9/2) spectra of BiPd₁₂AsL, BiPd₁₂AsL_N, and BiPd₁₂AsL_C revealed narrow peaks (ν_1/2 ∼ 200 Hz) at 5470 ppm with a longitudinal relaxation time in the millisecond range (at 8.46 T). The absence of a quadrupolar relaxation contribution could be attributed to the allocation of Bi^III in the highly symmetrical cuboid POP host cage. Similar peaks were absent in the ²⁰⁹Bi-NMR spectra of the star-shaped POPs BiPd₁₅P and BiPd₁₅PL due to the less symmetric coordination environment around the central Bi^III ion. Further, ^205/206Bi-radiolabeled POPs have been synthesized by incorporating a ^205/206Bi^III ion in the center of the POP structures. Carrier-free ^205/206Bi radioisotopes (as surrogates of α-emitting ²¹³Bi) were incorporated into the POP host-cage for the preparation of ^205/206BiPd₁₂AsL, ^205/206BiPd₁₂AsL_N, ^205/206BiPd₁₂AsL_C, and ^205/206BiPd₁₅PL, respectively. The radiometal incorporation was complete (>99% radiochemical yield) in 10 min according to radio-thin-layer chromatography. The ^205/206BiPd₁₂AsL polyanion was purified by solid-phase extraction. The incubation in rat serum showed the formation of a ^205/206BiPd₁₂AsL-protein aggregate.

Indium in Polyoxopalladate(II) Chemistry: Synthesis of All-Acetate-Capped [InPd12O8(OAc)16]5- and Controlled Transformation to Phosphate-Capped Double-Cube and Monocube

We have prepared the indium(III)-centered, all-acetate-capped polyoxopalladate(II) nanocube [InPd₁₂O₈(OAc)₁₆]^5- (InPd₁₂Ac₁₆), which can be further used as precursor to form the phosphate-capped (i) double-cube [In₂Pd₂₃O₁₇(OH)(PO₄)₁₂(PO₃OH)]^21- (In₂Pd₂₃P₁₃) and (ii) monocube [InPd₁₂O₈(PO₄)₈]^13- (InPd₁₂P₈). All three novel polyoxopalladates (POPs) were synthesized using conventional one-pot techniques in aqueous solution and characterized in the solid state (single-crystal XRD, IR, elemental analysis), in solution (¹¹⁵In, ³¹P, and ¹³C NMR), and in the gas phase (ESI-MS).

PIDAZTA: Structurally Constrained Chelators for the Efficient Formation of Stable Gallium-68 Complexes at Physiological pH

Two structurally constrained chelators based on a fused bicyclic scaffold, 4-amino-4-methylperhydro-pyrido[1,2-a][1,4]diazepin-N,N',N'-triacetic acids [(4R*,10aS*)-PIDAZTA (L1) and (4R*,10aR*)-PIDAZTA (L2)], were designed for the preparation of Ga^III -based radiopharmaceuticals. The stereochemistry of the ligand scaffold has a deep impact on the properties of the complexes, with unexpected [Ga(L2)OH] species being superior in terms of both thermodynamic stability and inertness. This peculiar behavior was rationalized on the basis of molecular modeling and appears to be related to a better fit in size of Ga^III into the cavity of L2. Fast and efficient formation of the Ga^III chelates at room temperature was observed at pH values between 7 and 8, which enables ⁶⁸ Ga radiolabeling under truly physiological conditions (pH 7.4).

[Spontaneous haemothorax - thoracic surgeon and intervention radiologist successful cooperation]

The definition of spontaneous haemothorax is accumulation of blood within the pleural space without trauma or iatrogenic causes. A case of a 17-year-old male patient with a history of multiple abnormal arterial fistulas between systemic circulation and pulmonary circulation as a cause of bleeding is presented. An overview of the causes, the clinical features of haemothorax and the interventional radiological methods that can solve some causes of haemothorax are presented in connection of our case report.

Effect of the Nature of Donor Atoms on the Thermodynamic, Kinetic and Relaxation Properties of Mn(II) Complexes Formed With Some Trisubstituted 12-Membered Macrocyclic Ligands

During the past few years increasing attention has been devoted to Mn(II) complexes as possible substitutes for Gd(III) complexes as contrast agents in MRI. Equilibrium (log KMnL or pMn value), kinetic parameters (rates and half-lives of dissociation) and relaxivity of the Mn(II) complexes formed with 12-membered macrocyclic ligands were studied. The ligands were selected in a way to gain information on how the ligand rigidity, the nature of the donor atoms in the macrocycle (pyridine N, amine N, and etheric O atom), the nature of the pendant arms (carboxylates, phosphonates, primary, secondary and tertiary amides) affect the physicochemical parameters of the Mn(II) complexes. As expected, decreasing the denticity of DOTA (to afford DO3A) resulted in a drop in the stability and inertness of [Mn(DO3A)]- compared to [Mn(DOTA)]2-. This decrease can be compensated partially by incorporating the fourth nitrogen atom into a pyridine ring (e.g., PCTA) or by replacement with an etheric oxygen atom (ODO3A). Moreover, the substitution of primary amides for acetates resulted in a noticeable drop in the stability constant (PC3AMH), but it increased as the primary amides (PC3AMH) were replaced by secondary (PC3AMGly) or tertiary amide (PC3AMPip) pendants. The inertness of the Mn(II) complexes behaved alike as the rates of acid catalyzed dissociation increased going from DOTA (k1 = 0.040 M-1s-1) to DO3A (k1 = 0.45 M-1s-1). However, the rates of acid catalyzed dissociation decreased from 0.112 M-1s-1 observed for the anionic Mn(II) complex of PCTA to 0.0107 M-1s-1 and 0.00458 M-1s-1 for the cationic Mn(II) complexes of PC3AMH and PC3AMPip ligands, respectively. In spite of its lower denticity (as compared to DOTA) the sterically more hindered amide complex ([Mn(PC3AMPip)]2+) displays surprisingly high conditional stability (pMn = 8.86 vs. pMn = 9.74 for [Mn(PCTA)]-) and excellent kinetic inertness. The substitution of phosphonates for the acetate pendant arms (DOTP and DO3P), however, resulted in a noticeable drop in the conditional stability as well as dissociation kinetic parameters of the corresponding Mn(II) complexes ([Mn(DOTP)]6- and [Mn(DO3P)]4-) underlining that the phosphonate pedant should not be considered as a suitable building block for further ligand design while the tertiary amide moiety will likely have some implications in this respect in the future.

Dithallium(III)-Containing 30-Tungsto-4-phosphate, [Tl2Na2(H2O)2(P2W15O56)2]16-: Synthesis, Structural Characterization, and Biological Studies

Here we report on the synthesis and structural characterization of the dithallium(III)-containing 30-tungsto -4-phosphate [Tl₂Na₂(H₂O)₂{P₂W₁₅O₅₆}₂]^16- (1) by a multitude of solid-state and solution techniques. Polyanion 1 comprises two octahedrally coordinated Tl³⁺ ions sandwiched between two trilacunary {P₂W₁₅} Wells-Dawson fragments and represents only the second structurally characterized, discrete thallium-containing polyoxometalate to date. The two outer positions of the central rhombus are occupied by sodium ions. The title polyanion is solution-stable as shown by ³¹P and ^203/205Tl NMR. This was also supported by Tl NMR spectra simulations including several spin systems of isotopologues with half-spin nuclei (²⁰³Tl, ²⁰⁵Tl, ³¹P, ¹⁸³W). ²³Na NMR showed a time-averaged signal of the Na⁺ counter cations and the structurally bonded Na⁺ ions. ^203/205Tl NMR spectra also showed a minor signal tentatively attributed to the trithallium-containing derivative [Tl₃Na(H₂O)₂(P₂W₁₅O₅₆)₂]^14-, which could also be identified in the solid state by single-crystal X-ray diffraction. The bioactivity of polyanion 1 was also tested against bacteria and Leishmania.

Equilibrium Thermodynamics, Formation, and Dissociation Kinetics of Trivalent Iron and Gallium Complexes of Triazacyclononane-Triphosphinate (TRAP) Chelators: Unraveling the Foundations of Highly Selective Ga-68 Labeling

In order to rationalize the influence of Fe^III contamination on labeling with the ⁶⁸Ga eluted from ⁶⁸Ge/⁶⁸Ga-generator, a detailed investigation was carried out on the equilibrium properties, formation and dissociation kinetics of Ga^III- and Fe^III-complexes of 1,4,7-triazacyclononane-1,4,7-tris(methylene[2-carboxyethylphosphinic acid]) (H₆TRAP). The stability and protonation constants of the [Fe(TRAP)]^3- complex were determined by pH-potentiometry and spectrophotometry by following the competition reaction between the TRAP ligand and benzhydroxamic acid (0.15 M NaNO₃, 25°C). The formation rates of [Fe(TRAP)] and [Ga(TRAP)] complexes were determined by spectrophotometry and ³¹P-NMR spectroscopy in the pH range 4.5-6.5 in the presence of 5-40 fold H_xTRAP^(x-6) excess (x = 1 and 2, 0.15 M NaNO₃, 25°C). The kinetic inertness of [Fe(TRAP)]^3- and [Ga(TRAP)]^3- was examined by the trans-chelation reactions with 10 to 20-fold excess of H_xHBED^(x-4) ligand by spectrophotometry at 25°C in 0.15 M NaCl (x = 0,1 and 2). The stability constant of [Fe(TRAP)]^3- (logK_FeL = 26.7) is very similar to that of [Ga(TRAP)]^3- (logK_GaL = 26.2). The rates of ligand exchange reaction of [Fe(TRAP)]^3- and [Ga(TRAP)]^3- with H_xHBED^(x-4) are similar. The reactions take place quite slowly via spontaneous dissociation of [M(TRAP)]^3-, [M(TRAP)OH]^4- and [M(TRAP)(OH)₂]^5- species. Dissociation half-lives (t_1/2) of [Fe(TRAP)]^3- and [Ga(TRAP)]^3- complexes are 1.1 × 10⁵ and 1.4 × 10⁵ h at pH = 7.4 and 25°C. The formation reactions of [Fe(TRAP)]^3- and [Ga(TRAP)]^3- are also slow due to the formation of the unusually stable monoprotonated [^*M(HTRAP)]^2- intermediates [^*logK_Ga(HL) = 10.4 and ^*logK_Fe(HL) = 9.9], which are much more stable than the [^*Ga(HNOTA)]⁺ intermediate [^*logK_Ga(HL) = 4.2]. Deprotonation and transformation of the monoprotonated [^*M(HTRAP)]^2- intermediates into the final complex occur via OH^--assisted reactions. Rate constants (k_OH) characterizing the OH^--driven deprotonation and transformation of [^* Ga(HTRAP)]^2- and [^*Fe(HTRAP)]^2- intermediates are 1.4 × 10⁵ M^-1s^-1 and 3.4 × 10⁴ M^-1s^-1, respectively. In conclusion, the equilibrium and kinetic properties of [Fe(TRAP)] and [Ga(TRAP)] complexes are remarkably similar due to the close physico-chemical properties of Fe^III and Ga^III-ions. However, a slightly faster formation of [Ga(TRAP)] over [Fe(TRAP)] provides a rationale for a previously observed, selective complexation of ⁶⁸Ga^III in presence of excess Fe^III.

Improved Efficacy of Synthesizing *MIII-Labeled DOTA Complexes in Binary Mixtures of Water and Organic Solvents. A Combined Radio- and Physicochemical Study

Typically, the synthesis of radiometal-based radiopharmaceuticals is performed in buffered aqueous solutions. We found that the presence of organic solvents like ethanol increased the radiolabeling yields of [⁶⁸Ga]Ga-DOTA (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacatic acid). In the present study, the effect of organic cosolvents [ethanol (EtOH), isopropyl alcohol, and acetonitrile] on the radiolabeling yields of the macrocyclic chelator DOTA with several trivalent radiometals (gallium-68, scandium-44, and lutetium-177) was systematically investigated. Various binary water (H₂O)/organic solvent mixtures allowed the radiolabeling of DOTA at a significantly lower temperature than 95 °C, which is relevant for the labeling of sensitive biological molecules. Simultaneously, much lower amounts of the chelators were required. This strategy may have a fundamental impact on the formulation of trivalent radiometal-based radiopharmaceuticals. The equilibrium properties and formation kinetics of [M(DOTA)]^- (M^III= Ga^III, Ce^III, Eu^III, Y^III, and Lu^III) complexes were investigated in H₂O/EtOH mixtures (up to 70 vol % EtOH). The protonation constants of DOTA were determined by pH potentiometry in H₂O/EtOH mixtures (0-70 vol % EtOH, 0.15 M NaCl, 25 °C). The log K₁^H and log K₂^H values associated with protonation of the ring N atoms decreased with an increase of the EtOH content. The formation rates of [M(DOTA)]^- complexes increase with an increase of the pH and [EtOH]. Complexation occurs through rapid formation of the diprotonated [M(H₂DOTA)]⁺ intermediates, which are in equilibrium with the kinetically active monoprotonated [M(HDOTA)] intermediates. The rate-controlling step is deprotonation (and rearrangement) of the monoprotonated intermediate, which occurs through H₂O (^*M(HL) k_H2O) and OH^- (^*M(HL) k_OH) assisted reaction pathways. The rate constants are essentially independent of the EtOH concentration, but the ^M(HL) k_H2O values increase from Ce^III to Lu^III. However, the log K_M(HL)^H protonation constants, analogous to the log K^H₂ value, decrease with increasing [EtOH], which increases the concentration of the monoprotonated M(HDOTA) intermediate and accelerates formation of the final complexes. The overall rates of complex formation calculated by the obtained rate constants at different EtOH concentrations show a trend similar to that of the complexation rates determined with the use of radioactive isotopes.

Coordination Properties of GdDO3A-Based Model Compounds of Bioresponsive MRI Contrast Agents

We report a detailed characterization of the thermodynamic stability and dissociation kinetics of Gd³⁺ complexes with DO3A derivatives containing a (methylethylcarbamoylmethylamino)acetic acid (L¹), (methylpropylcarbamoylmethylamino)acetic acid (L²), 2-dimethylamino- N-ethylacetamide (L³), or 2-dimethylamino- N-propylacetamide (L⁴) group attached to the fourth nitrogen atom of the macrocyclic unit. These ligands are model systems of Ca²⁺- and Zn²⁺-responsive contrast agents (CA) for application in magnetic resonance imaging (MRI). The results of the potentiometric studies ( I = 0.15 M NaCl) provide stability constants with log K_GdL values in the range 13.9-14.8. The complex speciation in solution was found to be quite complicated due to the formation of protonated species at low pH, hydroxido complexes at high pH, and stable dinuclear complexes in the case of L^1,2. At neutral pH significant fractions of the complexes are protonated at the amine group of the amide side chain (log K_GdL×H = 7.2-8.1). These ligands form rather weak complexes with Mg²⁺ and Ca²⁺ but very stable complexes with Cu²⁺ (log K_CuL = 20.4-22.3) and Zn²⁺ (log K_ZnL = 15.5-17.6). Structural studies using a combination of ¹H NMR and luminescence spectroscopy show that the amide group of the ligand is coordinated to the metal ion at pH ∼8.5, while protonation of the amine group provokes the decoordination of the amide O atom and a concomitant increase in the hydration number and proton relaxivity. The dissociation of the complexes occurs mainly through a rather efficient proton-assisted pathway, which results in kinetic inertness comparable to that of nonmacrocyclic ligands such as DTPA rather than DOTA-like complexes.

Taking the next step toward inert Mn2+ complexes of open-chain ligands: the case of the rigid PhDTA ligand

Equilibrium, dissociation kinetics, relaxometric and electrochemical properties of the [Mn(PhDTA)]²⁻ complex were investigated and the structure of the [Mn(PhDTA)]²⁻ complex was studied by using DFT calculations.

Gallium(III) chelates of mixed phosphonate-carboxylate triazamacrocyclic ligands relevant to nuclear medicine: Structural, stability and in vivo studies

Three triaza macrocyclic ligands, H₆NOTP (1,4,7-triazacyclononane-N,N',N″-trimethylene phosphonic acid), H₄NO2AP (1,4,7-triazacyclononane-N-methylenephosphonic acid-N',N″-dimethylenecarboxylic acid), and H₅NOA2P (1,4,7-triazacyclononane-N,N'-bis(methylenephosphonic acid)-N″-methylene carboxylic acid), and their gallium(III) chelates were studied in view of their potential interest as scintigraphic and PET (Positron Emission Tomography) imaging agents. A ¹H, ³¹P and ⁷¹Ga multinuclear NMR study gave an insight on the structure, internal dynamics and stability of the chelates in aqueous solution. In particular, the analysis of ⁷¹Ga NMR spectra gave information on the symmetry of the Ga³⁺ coordination sphere and the stability of the chelates towards hydrolysis. The ³¹P NMR spectra afforded information on the protonation of the non-coordinated oxygen atoms from the pendant phosphonate groups and on the number of species in solution. The ¹H NMR spectra allowed the analysis of the structure and the number of species in solution. ³¹P and ¹H NMR titrations combined with potentiometry afforded the measurement of the protonation constants (log K_Hi) and the microscopic protonation scheme of the triaza macrocyclic ligands. The remarkably high thermodynamic stability constant (log K_GaL=34.44 (0.04) and stepwise protonation constants of Ga(NOA2P)^2- were determined by potentiometry and ⁶⁹Ga and ³¹P NMR titrations. Biodistribution and gamma imaging studies have been performed on Wistar rats using the radiolabeled ⁶⁷Ga(NO2AP)^- and ⁶⁷Ga(NOA2P)^2-chelates, having both demonstrated to have renal excretion. The correlation of the molecular properties of the chelates with their pharmacokinetic properties has been analysed.

Equilibrium, Kinetic and Structural Properties of Gallium(III) and Some Divalent Metal Complexes Formed with the New DATAm and DATA5m Ligands

The development of ⁶⁸ Ge/⁶⁸ Ga generators has made the positron-emitting ⁶⁸ Ga isotope widely accessible and raised interest in new chelate complexes of Ga³⁺ . The hexadentate 1,4-di(acetate)-6-methyl[amino(methyl)acetate]perhydro-1,4-diazepane (DATA^m ) ligand and its bifunctional analogue, 1,4-di(acetate)-6-pentanoic acid[amino(methyl)acetate]perhydro-1,4-diazepane (DATA^5m ), rapidly form complexes with ⁶⁸ Ga in high radiochemical yield. The stability constants of DATA^m and DATA^5m complexes formed with Ga³⁺ , Zn²⁺ , Cu²⁺ , Mn²⁺ and Ca²⁺ have been determined by using pH potentiometry, spectrophotometry (Cu²⁺ ) and ¹ H and ⁷¹ Ga NMR spectroscopy (Ga³⁺ ). The stability constants of Ga(DATA^m ) and Ga(DATA^5m ) complexes are slightly higher than those of Ga(AAZTA). The species distribution calculations indicated the predominance of Ga(L)OH mixed-hydroxo complexes at physiological pH. The ¹ H and ⁷¹ Ga NMR spectroscopy studies provided information about the coordinated functional groups of ligands and on the kinetics of exchange between the Ga(L) and Ga(L)OH complexes. The transmetalation reactions between the Ga(L) complexes and Cu²⁺ citrate (6<pH<8.5) occur through both spontaneous and OH^- -assisted dissociation of the Ga(L)OH species. At pH 7.4 and 25 °C, the half-lives of the dissociation of Ga(DATA^m ), Ga(DATA^5m ) and Ga(AAZTA) were 11, 44 and 24 h, respectively. Similar half-lives have been obtained for the ligand-exchange reactions between the Ga(L)OH complexes and transferrin. The equilibrium and kinetic data indicate that the Ga(DATA^5m ) complex is a good ⁶⁸ Ga-based radiodiagnostic candidate.

[A giant inflammatory fibroid polyp of the esophagus]

Inflammatory fibroid polyp (IFP) is an uncommon benign tumor of the gastrointestinal tract. IFP in the esophagus is very rare, in particular in giant size. A case of a 63 year old woman with a 13 × 7 × 4.5 cm polyp originated of the lower third of the oesophagus is presented. Her esophageal polyp extended proximally from the level of the tracheal bifurcation, prolapsing through the cardia as well as the herniated stomach, and entered distally into the abdominal part of the stomach. Resection of the polyp was performed via a right oesophago-gastrotomy. Histology verified inflammatory fibroid polyp of the esophagus. An overview of clinical features of the inflammatory fibroid polyp is presented in connection of our case report.

Simple (17) O NMR method for studying electron self-exchange reaction between UO2 (2+) and U(4+) aqua ions in acidic solution

(17) O NMR spectroscopy is proven to be suitable and convenient method for studying the electron exchange by following the decrease of (17) O-enrichment in U(17) OO(2+) ion in the presence of U(4+) ion in aqueous solution. The reactions have been performed at room temperature using I = 5 M ClO4 (-) ionic medium in acidic solutions in order to determine the kinetics of electron exchange between the U(4+) and UO2 (2+) aqua ions. The rate equation is given as R = a[H(+) ](-2)  + R', where R' is an acid independent parallel path. R' depends on the concentration of the uranium species according to the following empirical rate equation: R' = k1 [UO(2 +) ](1/2) [U(4 +) ](1/2)  + k2 [UO(2 +) ](3/2) [U(4 +) ](1/2) . The mechanism of the inverse H(+) concentration-dependent path is interpreted as equilibrium formation of reactive UO2 (+) species from UO2 (2+) and U(4+) aqua ions and its electron exchange with UO2 (2+) . The determined rate constant of this reaction path is in agreement with the rate constant of UO2 (2+) -UO2 (+) , one electron exchange step calculated by Marcus theory, match the range given experimentally of it in an early study. Our value lies in the same order of magnitude as the recently calculated ones by quantum chemical methods. The acid independent part is attributed to the formation of less hydrolyzed U(V) species, i.e. UO(3+) , which loses enrichment mainly by electron exchange with UO2 (2+) ions. One can also conclude that (17) O NMR spectroscopy, or in general NMR spectroscopy with careful kinetic analysis, is a powerful tool for studying isotope exchange reactions without the use of sophisticated separation processes. Copyright © 2015 John Wiley & Sons, Ltd.

High kinetic inertness of a bis-hydrated Gd-complex with a constrained AAZTA-like ligand

The Gd^III complex of a cyclohexyl-fused AAZTA derivative shows the highest kinetic inertness in the class of non-macrocyclic bis hydrated Gd^III-complexes and optimal relaxometric performances.

Virulence and antimicrobial resistance determinants of verotoxigenic Escherichia coli (VTEC) and of multidrug-resistant E. coli from foods of animal origin illegally imported to the EU by flight passengers

The aim of this study was to reveal phenotype/genotype characteristics of verotoxigenic Escherichia coli (VTEC) and multidrug resistant E. coli in food products of animal origin confiscated as illegal import at Austrian, German and Slovenian airports. VTEC isolates were obtained by using ISO guidelines 16654:2001 for O157 VTEC or ISO/ TS13136:2012 for non-O157 VTEC, with additional use of the RIDASCREEN® Verotoxin immunoassay. The testing of 1526 samples resulted in 15 VTEC isolates (1.0%) primarily isolated from hard cheese from Turkey and Balkan countries. Genotyping for virulence by using a miniaturized microarray identified a wide range of virulence determinants. One VTEC isolate (O26:H46) possessing intimin (eae) and all other essential genes of Locus of Enterocyte Effacement (LEE) was designated as enterohemorrhagic E. coli (EHEC). None of the other VTEC strains belonged to serogroups O157, O145, O111, O104 or O103. VTEC strains harbored either stx(1) (variants stx1(a) or stx(1c)) or st(x2) (variants stx(2a), stx(2b), stx(2a/d) or stx(2c/d)) genes. Pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) demonstrated high genetic diversity and identified three new sequence types (STs): 4505, 4506 and 4507. Food samples collected from the Vienna airport were also tested for E. coli quantities using the ISO 16649:2001, and for detection of multidrug resistant phenotypes and genotypes. The resulting 113 commensal E. coli isolates were first tested in a pre-screening against 6 selected antimicrobials to demonstrate multidrug resistance. The resulting 14 multidrug resistant (MDR) E. coli isolates, representing 0.9% of the samples, were subjected to further resistance phenotyping and to microarray analyses targeting genetic markers of antimicrobial resistance and virulence. Genotyping revealed various combinations of resistance determinants as well as the presence of class 1, class 2 integrons. The isolates harbored 6 to 11 antibiotic resistance genes as well as 1 to 14 virulence genes. In this panel of 14 MDR E. coli two strains proved to carry CTX-M type ESBLs, and one single isolate was identified as enteropathogenic E. coli (EPEC). In general, isolates carrying a high number of resistance determinants had lower number of virulence genes and vice versa. In conclusion, this first pilot study on the prevalence of VTEC and of MDR/ESBL E. coli in illegally imported food products of animal origin suggests that these strains could represent reservoirs for dissemination of potentially new types of pathogenic and MDR E. coli in Europe.

A shortcut to high-affinity Ga-68 and Cu-64 radiopharmaceuticals: one-pot click chemistry trimerisation on the TRAP platform

Due to its 3 carbonic acid groups being available for bioconjugation, the TRAP chelator (1,4,7-triazacyclononane-1,4,7-tris(methylene(2-carboxyethylphosphinic acid))) is chosen for the synthesis of trimeric bioconjugates for radiolabelling. We optimized a protocol for bio-orthogonal TRAP conjugation via Cu(I)-catalyzed Huisgen-cycloaddition of terminal azides and alkynes (CuAAC), including a detailed investigation of kinetic properties of Cu(II)-TRAP complexes. TRAP building blocks for CuAAC, TRAP(alkyne)3 and TRAP(azide)3 were obtained by amide coupling of propargylamine/3-azidopropyl-1-amine, respectively. For Cu(II) complexes of neat and triply amide-functionalized TRAP, the equilibrium properties as well as pseudo-first-order Cu(II)-transchelation, using 10 to 30 eq. of NOTA and EDTA, were studied by UV-spectrophotometry. Dissociation of any Cu(II)-TRAP species was found to be independent on the nature or excess of a competing chelator, confirming a proton-driven two-step mechanism. The respective thermodynamic stability constants (log K(ML): 19.1 and 17.6) and dissociation rates (k: 38 × 10(-6) and 7 × 10(-6) s(-1), 298 K, pH 4) show that the Cu(II) complex of the TRAP-conjugate possesses lower thermodynamic stability but higher kinetic inertness. At pH 2-3, its demetallation with NOTA was complete within several hours/days at room temperature, respectively, enabling facile Cu(II) removal after click coupling by direct addition of NOTA trihydrochloride to the CuAAC reaction mixture. Notwithstanding this, an extrapolated dissociation half life of >100 h at 37 °C and pH 7 confirms the suitability of TRAP-bioconjugates for application in Cu-64 PET (cf. t(1/2)(Cu-64) = 12.7 h). To showcase advantages of the method, TRAP(DUPA-Pep)3, a trimer of the PSMA inhibitor DUPA-Pep, was synthesized using 1 eq. TRAP(alkyne)3, 3.3 eq. DUPA-Pep-azide, 10 eq. Na ascorbate, and 1.2 eq. Cu(II)-acetate. Its PSMA affinity (IC50), determined by the competition assay on LNCaP cells, was 18-times higher than that of the corresponding DOTAGA monomer (IC50: 2 ± 0.1 vs. 36 ± 4 nM), resulting in markedly improved contrast in Ga-68-PET imaging. In conclusion, the kinetic inertness profile of Cu(II)-TRAP conjugates allows for simple Cu(II) removal after click functionalisation by means of transchelation, but also confirms their suitability for Cu-64-PET as demonstrated previously (Dalton Trans., 2012, 41, 13803).

[Tl(III)(dota)](-): An Extraordinarily Robust Macrocyclic Complex

The X-ray structure of {C(NH2)3}[Tl(dota)]·H2O shows that the Tl(3+) ion is deeply buried in the macrocyclic cavity of the dota(4-) ligand (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate) with average Tl-N and Tl-O distances of 2.464 and 2.365 Å, respectively. The metal ion is directly coordinated to the eight donor atoms of the ligand, which results in a twisted square antiprismatic (TSAP') coordination around Tl(3+). A multinuclear (1)H, (13)C, and (205)Tl NMR study combined with DFT calculations confirmed the TSAP' structure of the complex in aqueous solution, which exists as the Λ(λλλλ)/Δ(δδδδ) enantiomeric pair. (205)Tl NMR spectroscopy allowed the protonation constant associated with the protonation of the complex according to [Tl(dota)](-) + H(+) ⇆ [Tl(Hdota)] to be determined, which turned out to be pK(H)Tl(dota) = 1.4 ± 0.1. [Tl(dota)](-) does not react with Br(-), even when using an excess of the anion, but it forms a weak mixed complex with cyanide, [Tl(dota)](-) + CN(-) ⇆ [Tl(dota)(CN)](2-), with an equilibrium constant of Kmix = 6.0 ± 0.8. The dissociation of the [Tl(dota)](-) complex was determined by UV-vis spectrophotometry under acidic conditions using a large excess of Br(-), and it was found to follow proton-assisted kinetics and to take place very slowly (∼10 days), even in 1 M HClO4, with the estimated half-life of the process being in the 10(9) h range at neutral pH. The solution dynamics of [Tl(dota)](-) were investigated using (13)C NMR spectroscopy and DFT calculations. The (13)C NMR spectra recorded at low temperature (272 K) point to C4 symmetry of the complex in solution, which averages to C4v as the temperature increases. This dynamic behavior was attributed to the Λ(λλλλ) ↔ Δ(δδδδ) enantiomerization process, which involves both the inversion of the macrocyclic unit and the rotation of the pendant arms. According to our calculations, the arm-rotation process limits the Λ(λλλλ) ↔ Δ(δδδδ) interconversion.

Stereoselective coordination: a six-membered P,N-chelate tailored for asymmetric allylic alkylation

Six-membered chelate complexes [Pd(1a–b)Cl₂], (2a–b) and [Pd(1a–b)(η³-PhCHCHCHPh)]BF₄, (3a–b) of P,N-type ligands 1a, ((2S,4S)-2-diphenyl-phosphino-4-isopropylamino-pentane) and 1b, ((2S,4S)-2-diphenyl-phosphino-4-methylamino-pentane) have been prepared.

Solution structures, stabilities, kinetics, and dynamics of DO3A and DO3A-sulphonamide complexes

The Gd(3+)-DO3A-arylsulphonamide (DO3A-SA) complex is a promising pH-sensitive MRI agent. The stability constants of the DO3A-SA and DO3A complexes formed with Mg(2+), Ca(2+), Mn(2+), Zn(2+), and Cu(2+) ions are similar, whereas the logKLnL values of Ln(DO3A-SA) complexes are 2 orders of magnitude higher than those of the Ln(DO3A) complexes. The protonation constant (log KMHL) of the sulphonamide nitrogen in the Mg(2+), Ca(2+), Mn(2+), Zn(2+), and Cu(2+) complexes is very similar to that of the free ligand, whereas the logKLnHL values of the Ln(DO3A-SA) complexes are lower by about 4 logK units, indicating a strong interaction between the Ln(3+) ions and the sulphonamide N atom. The Ln(HDO3A-SA) complexes are formed via triprotonated *Ln(H3DO3A-SA) intermediates which rearrange to the final complex in an OH(-)-assisted deprotonation process. The transmetalation reaction of Gd(HDO3A-SA) with Cu(2+) is very slow (t1/2 = 5.6 × 10(3) h at pH = 7.4), and it mainly occurs through proton-assisted dissociation of the complex. The (1)H and (13)C NMR spectra of the La-, Eu-, Y-, and Lu(DO3A-SA) complexes have been assigned using 2D correlation spectroscopy (COSY, EXSY, HSQC). Two sets of signals are observed for Eu-, Y-, and Lu(DO3A-SA), showing two coordination isomers in solution, that is, square antiprismatic (SAP) and twisted square antiprismatic (TSAP) geometries with ratios of 86-14, 93-7, and 94-6%, respectively. Line shape analysis of the (13)C NMR spectra of La-, Y- , and Lu(DO3A-SA) gives higher rates and lower activation entropy values compared to Ln(DOTA) for the arm rotation, which indicates that the Ln(DO3A-SA) complexes are less rigid due to the larger flexibility of the ethylene group in the sulphonamide pendant arm. The fast isomerization and the lower activation parameters of Ln(DO3A-SA) have been confirmed by theoretical calculations in vacuo and by using the polarizable continuum model. The solid state X-ray structure of Cu(H2DO3A-SA) shows distorted octahedral coordination. The coordination sites of Cu(2+) are occupied by two ring N- and two carboxylate O-atoms in equatorial position. The other two ring N-atoms complete the coordination sphere in axial positions. The solid state structure also indicates that a carboxylate O atom and the sulphonamide nitrogen are protonated and noncoordinated.