A Rotational Study of 2-tert-Butylphenol and Its 1 : 1 Argon Complex

The chirped-pulse Fourier Transform microwave spectrum of 2-tert-butylphenol, an industrial intermediate for the production of antioxidants, has been investigated in the 2-8 GHz frequency range. The spectral analysis has allowed obtaining precise structural information on the most stable conformer and its complex with argon. The conformation of the monomer reveals that the hydroxyl group is coplanar with the ring but points in the opposite direction to the tert-butyl group, reducing steric interactions. In the tert-butyl group one methyl group is coplanar and the other two are symmetrically staggered respect to the ring. The complex shows the rare gas sitting above the aromatic ring. Interestingly, neither the monomer nor the complex exhibit large-amplitude hydroxyl torsion motions, previously observed in 2,6-disubstituted phenols such as 2,6-di-tert-butylphenol or propofol. The experimental results are supported by computational calculations, validating the molecular structure. Additionally, symmetry-adapted perturbation theory has allowed determining the van der Waals intermolecular interaction energy of the complex.

Structure and dynamics of 3'-aminoacetophenone and 4'-aminoacetophenone from rotational spectroscopy

The rotational spectra of 4'-aminoacetophenone, and those of two conformers (Z and E arrangement of the CO and NH2 groups) of 3'-aminoacetophenone and their 13C and 15N isotopologues were investigated both in the microwave (2-8 GHz) and millimetre (59.6-74.4 GHz) frequency regions using chirped pulse Fourier transform and free-jet absorption techniques, respectively. The spectra consist of μa and μb type lines that show a hyperfine structure due to both the nuclear quadrupole coupling of the 14N nucleus and the methyl internal rotation. Relative intensity measurements show that the Z form in 3'-aminoacetophenone is favoured with respect to E and the measured energy difference upper limit is about 5.5(1) kJ mol-1. Barriers to methyl internal rotation are V3 = 7.04(2) and 6.530(6) kJ mol-1 for 3'(Z)- and 4'-aminoacetophenone, respectively. Flexible model analyses of the amino inversion motion based on ab initio potential energy paths, suggest that the corresponding vibrational splitting increases up to 78% from aniline to 3'(E)-, 3'(Z), and 4-aminoacetophenone. However, due to supersonic expansion cooling, no splitting related to amine inversion is observed.

The Structure of 2,6-Di-tert-butylphenol-Argon by Rotational Spectroscopy

The molecular structure of a van der Waals-bonded complex involving 2,6-di-tert-butylphenol and a single argon atom has been determined through rotational spectroscopy. The experimentally derived structural parameters were compared to the outcomes of quantum chemical calculations that can accurately account for dispersive interactions in the cluster. The findings revealed a π-bound configuration for the complex, with the argon atom engaging the aromatic ring. The microwave spectrum reveals both fine and hyperfine tunneling components. The main spectral doubling is evident as two distinct clusters of lines, with an approximate separation of 179 MHz, attributed to the torsional motion associated with the hydroxyl group. Additionally, each component of this doublet further splits into three components, each with separations measuring less than 1 MHz. Investigation into intramolecular dynamics using a one-dimensional flexible model suggests that the main tunneling phenomenon originates from equivalent positions of the hydroxyl group. A double-minimum potential function with a barrier of 1000 (100) cm-1 effectively describes this extensive amplitude motion. However, the three-fold fine structure, potentially linked to internal motions within the tert-butyl group, requires additional scrutiny for a comprehensive understanding.

Rotational Spectroscopy Probes Lone Pair···π-Hole Interactions in Hexafluorobenzene-Tertiary Alkylamines Complexes

We employed microwave spectroscopy to investigate the 1:1 complexes of hexafluorobenzene with trimethylamine and quinuclidine, respectively. These complexes exhibit a C_3v symmetry and are stabilized by nitrogen lone pair···π-hole interactions along the C₃ axes. The N···π-center distances were determined to be 3.110(1) and 3.040(2) Å, respectively, which are shorter than that of hexafluorobenzene-ammonia at 3.2685(3) Å. Additionally, the strength of the intermolecular interaction increases with cluster size. While it was initially expected that the electron-donating effect of alkyl groups was responsible for changing the N···π interaction, the symmetry-adapted perturbation theory analysis revealed that, from hexafluorobenzene-ammonia to both hexafluorobenzene-alkylamines, electrostatic interaction actually decreases while dispersion interaction increases and becomes dominant. Interestingly, dispersion interaction decreases while electrostatic interaction increases from C₆F₆-N(CH₃)₃ to C₆F₆-NC₇H₁₃. The splitting pattern of the spectra indicates hexafluorobenzene rotates freely relative to its partners along the axis of the N···π-hole interactions.

Do people with multiple sclerosis perceive upper limb improvements from robotic-mediated therapy? A mixed methods study

BACKGROUND

Robot-mediated training is increasingly considered as a rehabilitation intervention targeting upper limb disability. However, experiences of such an intervention have been rarely explored in the multiple sclerosis population. This mixed methods study sought to explore the impact of an eight week upper limb robotic intervention on experiences of people with multiple sclerosis.

METHODS

Eleven participants (Median EDSS- score: 6.5) with moderate to severe upper limb impairment, performed eight week robot- mediated training of the most affected arm. The training involved a virtual learning platform called I-TRAVLE with duration of 30 min per training session, twice to three times per week. Two subjective questionnaires with items from the Intrinsic Motivation Inventory (IMI) and Credibility and Expectancy Questionnaire (CEQ) were collected bi-weekly during the intervention. Approximately one month after completing the training, three focus groups were conducted. Main themes were identified using thematic analysis.

RESULTS

Results from the IMI and CEQ indicated high patient satisfaction and expectation that the intervention will be beneficial for them. Two main themes were identified: (1) Effect of the intervention on impairment and activity in that participants felt that there was a positive impact of the training on strength, endurance and during activities of daily living and that it met their expectations; (2) Experiences based on system usage from the system in that participants expressed feelings of motivation and self-improvement. The participants also perceived the training as enjoyable and concluded that the use of games instigated a competitive spirit between the participants.

CONCLUSIONS

Robot-mediated training could have a motivating effect and induce a general positive experience while reducing disabilities of people with multiple sclerosis.

How Water Interacts with the NOH Group: The Rotational Spectrum of the 1:1 N,N-diethylhydroxylamine·Water Complex

The rotational spectrum of the 1:1 N,N-diethylhydroxylamine-water complex has been investigated using pulsed jet Fourier transform microwave spectroscopy in the 6.5-18.5 GHz frequency region. The most stable conformer has been detected as well as the 13C monosubstituted isotopologues in natural abundance and the 18O enriched water species, allowing to determine the nitrogen nuclear quadrupole coupling constants and the molecular structure in the vibrational ground state. The molecule has a Cs symmetry and the water lies in the bc symmetry plane forming two hydrogen bonds with the NOH frame with length: dHOH·NOH = 1.974 Å and dH2O·HON = 2.096 Å. From symmetry-adapted perturbation theory calculations coupled to atoms in molecule approach, the corresponding interaction energy values are estimated to be 24 and 13 kJ·mol-1, respectively. The great strength of the intermolecular interaction involving the nitrogen atom is in agreement with the high reactivity of hydroxylamine compounds at the nitrogen site.

Spectroscopic and quantum mechanical study of a scavenger molecule: N,N-diethylhydroxylamine

We report a combination of quantum mechanical calculations and a range of spectroscopic measurements in the gas phase of N,N-diethylhydroxylamine, an important scavenger compound. Three conformers were observed by pulsed jet Fourier transform microwave spectroscopy in the 6.5-18.5 GHz frequency range. They are characterized by the hydroxyl hydrogen atom being in trans orientation with respect to the bisector of the CNC angle while the side alkyl chains can be both trans (global minimum, C_s symmetry, A = 7608.1078(4), B = 2020.2988(2) and C = 1760.5423(2) MHz) or one trans and the other gauche (second energy minimum, A = 5302.896(1), B = 2395.9822(4) and C = 1804.8567(3) MHz) or gauche' (third energy minimum, A = 5960.8025(6), B = 2273.6627(4) and C = 1975.8074(4) MHz). For the global minimum, the ¹³C_α,¹³C_β and ¹⁵N isotopologues were observed in natural abundance, allowing for an accurate partial structure determination. Moreover, several lines were detected by free jet absorption millimeter wave spectroscopy in the 59.6-74.4 GHz spectral range. The electron binding energies of the highest occupied molecular orbital and the next-to-highest occupied molecular orbital, determined by photoelectron spectroscopy, are 8.95 and 10.76 eV, respectively. Supporting calculations evidence that, (i) upon ionization of the HOMO, the molecular structure changes from an amine to an N-oxoammonium arrangement and (ii) the 0-0 of the HOMO-1 photoionization is 10.46 eV. The K-shell binding energies, determined by X-ray photoelectron spectroscopy, are 290.42 eV (C_β), 291.45 eV (C_α), 405.98 eV (N) and 538.75 eV (O). The Fourier transform near infrared spectrum is reported and a tentative assignment is proposed. The equilibrium wavenumber (ω̃ = 3811 cm^-1) and the anharmonicity constant (ω̃χ = -87.5 cm^-1) of the hydroxyl stretching mode were estimated using a quadratic model.

Unusual Combination of Gastrointestinal Pathogens Detected by Multiplex PCR

Introduction/Objective

Infectious gastroenteritis (IGE) is a common but complex entity which is a major cause of global morbidity and mortality. IGE is caused by a wide range of etiologic agents such as viruses, bacteria, and parasites. In the United States there are approximately 373 million of IGE cases per year. Most cases of IGE resolve without identification of a specific pathogen. Multiplex molecular assays allow identification of multiple possible pathogens with rapid turnaround time and increased sensitivity, facilitating to formulate an effective treatment plan and control measures.

Methods/Case Report

We present a case of a pediatric patient with no significant past medical history who has been having runny stools that have progressively worsened in the last 3 months and 2 days history of bloody stools with mucus before emergency room presentation. She had no fever, vomiting, joint pain, oral ulcer, and rash. Physical exam showed that the patient appeared well, nontoxic, and vital signs were within normal limit. Copious rhinorrhea was noted. She was at 50th percentile for age on the growth chart. Family denied any recent travel or sick contacts however stated that all the family members have been on well water. Complete blood count was obtained and showed a platelet count of 669 x 10(3)/mcL and WBC of 16.6 x 10(3)/mcL with differential showing absolute lymphocytosis, absolute monocytosis and absolute eosinophilia. Biofire FilmArray gastrointestinal panel performed on the stool detected Giardia lamblia, Campylobacter, Shiga-like toxin producing E. coli and Adenovirus F 40/41. Repeat of the panel per protocol detected the same four pathogens.

Results (if a Case Study enter NA)

N/A.

Conclusion

This case report highlights the significance of detecting multiple causative pathogens. While long term watery diarrhea may guide clinicians to malabsorptive process and the use of well water to Giardia, a sensitive and specific multiplex assay can detect all the pathogens involved in the disease process and greatly simplify the treatment plan for patients. This unusual combination of pathogens can explain the unique symptomology of the patient including long term watery diarrhea, recent bloody diarrhea as well as copious rhinorrhea and failure to thrive.

Characterizing the Interactions of Dimethyl Sulfoxide with Water: A Rotational Spectroscopy Study

The interaction of dimethyl sulfoxide with water has been investigated by Fourier-transform microwave spectroscopy of the 1:1 complex and its isotopologues, complemented with quantum chemical calculations. The rotational spectra of ³⁴S and ¹³C isotopologues in natural abundance and the H₂¹⁸O and deuterated water enriched isotopologues have been measured, allowing a partial structure determination and establishing the position of water in the complex. In the most stable conformation water was found to be the donor of a primary OH···OS bond to the oxygen atom of dimethyl sulfoxide and acceptor of two weak CH···OH bonds with the methyl hydrogen atoms of dimethyl sulfoxide. From the structural determination confirmed by quantum chemical calculations, the water molecule lies in the symmetry plane of dimethyl sulfoxide, and the complex has an overall C_s symmetry. The experimental findings are supported by atoms in molecules and symmetry-adapted perturbation theories, which allowed for determining the hydrogen bond and intermolecular interaction energies, respectively.

Probing intra- and inter-molecular interactions through rotational spectroscopy: the case of the odorant 2'- aminoacetophenone and its 1:1 water and neon complexes

The chirped pulse Fourier transform microwave spectrum of 2'-aminoacetophenone, an aromatic chemical species with odorant properties, has been recorded in the 2-8 GHz frequency range and analysed, obtaining precise information on the structure of the monomer and its neon and water complexes.The conformation of the monomer is determined by the formation of a resonance-assisted hydrogen bond (RAHB) between the carbonyl and amino groups, which leads to the formation of a bicyclic-like aromatic structure.Accordingly, the cycle formed by the non-covalent bond is preferred to the phenyl ring as the interaction site for neon.In the 1:1 complex, water lies in the molecular plane and forms a strong hydrogen bond with the carbonyl group coupled to an ancillary interaction with the methyl group, leaving the intramolecular RAHB unchanged.The experimental findings are supported by atom in molecules and symmetry-adapted perturbation theories which allowed for determining the hydrogen bond and intermolecular interaction energies, respectively.

The Shapes of Sulfonamides: A Rotational Spectroscopy Study

Benzenesulfonamides are a class of molecules of extreme interest in the biochemical field because many of them are active against a variety of diseases. In this work, the pharmacophoric group benzensulfonamide, its derivatives para-toluensulfonamide and ortho-toluensulfonamide, and the bioactive molecule sulfanilamide, were investigated using rotational spectroscopy to determine their conformations and the influence of different substituents on their structures. For all species, the hyperfine structure due to the ¹⁴N atom was analyzed, and this provided crucial information for the unambiguous identification of the observed conformation of all molecules. In addition, for ortho-toluensulfonamide, the vibration–rotation hyperfine structure related to the methyl torsion was analyzed, and the methyl group rotation barrier was determined. For benzensulfonamide, partial r_S and r₀ structures were established from the experimental rotational constants of the parent and two deuterated isotopic species. In all compounds except ortho-toluensulfonamide, the amino group of the sulfonamide group lies perpendicular to the benzene plane with the aminic hydrogens eclipsing the oxygen atoms. In ortho-toluensulfonamide, where weak attractive interactions occur between the nitrogen lone pair and the methyl hydrogen atoms, the amino group lies in a gauche orientation, retaining the eclipsed configuration with respect to the SO₂ frame. A comparison of the geometrical arrangements found in the PDB database allowed us to understand that the bioactive conformations are different from those found in isolated conditions. The conformations within the receptor are reached with an energy cost, which is balanced by the interactions established in the receptor.

How Aromatic Fluorination Exchanges the Interaction Role of Pyridine with Carbonyl Compounds: The Formaldehyde Adduct

The rotational spectrum of the weakly bound complex pentafluoropyridine⋅⋅⋅formaldehyde has been investigated using Fourier transform microwave spectroscopy. From the analysis of the rotational parameters of the parent species and of the 13 C and 15 N isotopologues, the structural arrangement of the adduct has been unambiguously established. The full ring fluorination of pyridine has a dramatic effect on its binding properties: It alters the electron density distribution at the π-cloud of pyridine creating a π-hole and changing its electron donor-acceptor capabilities. In the complex, formaldehyde lies above the aromatic ring with one of the oxygen lone pairs, as conventionally envisaged, pointing toward its centre. This lone pair⋅⋅⋅π-hole interaction, reinforced by a weak C-H⋅⋅⋅N interaction, indicates an exchange of the electron-acceptor roles of both molecules when compared to the pyridine⋅⋅⋅formaldehyde adduct. Tunnelling doublets due to the internal rotation of formaldehyde have also been observed and analysed leading to a discussion on the competition between lone pair⋅⋅⋅π-hole and π⋅⋅⋅π stacking interactions.

σ-Hole activation and structural changes upon perfluorination of aryl halides: direct evidence from gas phase rotational spectroscopy

Enhancement of the σ-hole on the halogen atom of aryl halides due to perfluorination of the ring is demonstrated by use of the Extended Townes-Dailey (ETD) model coupled to a Natural Atomic Orbital Bond analysis on two perfluorinated aryl halides (C₆F₅Cl and C₆F₅Br) and their hydrogenated counterparts. The ETD analysis, which quantifies the halogen p-orbitals populations, relies on the nuclear quadrupole coupling constants which in this work are accurately determined experimentally from the rotational spectra. The rotational spectra investigated by Fourier-transform microwave spectroscopy performed in supersonic expansion are reported for the parent species of C₆F₅Cl and C₆F₅Br and their ¹³C, ³⁷Cl or ⁸¹Br substituted isotopologues observed in natural abundance. The experimentally determined rotational constants combined with theoretical data at the MP2/aug-cc-pVTZ level provide precise structural information from which an elongation of the ring along its symmetry axis due to perfluorination is proved.

Acute polymorphic psychosis: An interesting case report

Introduction

Acute Polymorphic Psychotic Disorder is a psychotic disorder with an acute onset, presenting thought and perception disorders variable into hours. Often, an emotional fluctuation is present and it may have a sudden onset and a rapid remission.

Objectives

The review’s objective is to manifest acute polymorhic psychotic disorders and possible effective medical interventions.

Methods

The current case concerns a 52-year old mother of 4 children with the manifestation of acute polymorphic psychotic disorder with a background of a stressful factor. The patient was involuntarily hospitalized in the Psychiatric Hospital of Thessaloniki from 04/01/ 2019 -21/ 01/2019 due to disorganization and acute confusing condition within the last 9 days. Delusional ideas of religious content were first observed, which alternated with ideas of greatness and then persecution, association and self-denial. She also presented auditory hallucinations while there was a fluctuation of emotion from excessive euphoria to depression. The patient had no previous hospitalization in a psychiatric clinic, however, 7 months ago she experienced another acute psychotic epeisode, while at the age of 17 and under the influence of intense stress, she described mood disorders.

Results

The current symptoms subsided after one week from the day of admission. During her hospitalization, a brain CT was performed without presence of pathological findings. Initially, her medication included i.m. haloperidol 15mg / ml daily, followed by a change to per os paliperidone 9mg daily.

Conclusions

Her mental status was improved, with no disturbances of consciousness noted and she was discharged on paliperidone as home medication.

Disclosure

No significant relationships.

Characterizing hydrogen and tetrel bonds in clusters of CO2 with carboxylic acids

The interaction between carbon dioxide and planar carboxylic acids has been investigated through the analysis of the microwave spectrum of the acrylic acid·CO2 complex and quantum chemical modeling of the R-COOH·(CO2)1,16 clusters, where R = H, CH2CH. As regards the 1 : 1 compounds, two species, involving the s-cis and s-trans conformers of acrylic acid were observed. For both of them, a similar bidentate interaction arises between the carbonyl group of CO2 and the carboxylic group of the organic acid, leading to the formation of a planar six-membered ring. The binding energy is estimated to be De ≃ 21 kJ mol-1, 1/3 being the energy contributions of the tetrel to hydrogen bonds, respectively. In the 1 : 16 clusters, the ring arrangement is broken, allowing for the interaction of the acid with several CO2 molecules. The CO2 molecules completely surround formic acid, whereas, in the case of acrylic acid, they tend to avoid the allyl chain.

Cellular remains in a ~3.42-billion-year-old subseafloor hydrothermal environment

Subsurface habitats on Earth host an extensive extant biosphere and likely provided one of Earth's earliest microbial habitats. Although the site of life's emergence continues to be debated, evidence of early life provides insights into its early evolution and metabolic affinity. Here, we present the discovery of exceptionally well-preserved, ~3.42-billion-year-old putative filamentous microfossils that inhabited a paleo-subseafloor hydrothermal vein system of the Barberton greenstone belt in South Africa. The filaments colonized the walls of conduits created by low-temperature hydrothermal fluid. Combined with their morphological and chemical characteristics as investigated over a range of scales, they can be considered the oldest methanogens and/or methanotrophs that thrived in an ultramafic volcanic substrate.

Interplay of Rotational and Pseudorotational Motions in Flexible Cyclic Molecules

Solutions to the time-independent nuclear Schrödinger equation associated with the pseudorotational motion of three flexible cyclic molecules are presented and discussed. Structural relaxations related to the pseudorotational motion are described as functions of a pseudorotation angle ϕ which is formulated according to the definition of ring-puckering coordinates originally proposed by Cremer and Pople ( J. Am. Chem. Soc. 1975, 97 (6), 1354-1358). In order to take into account the interplay between pseudorotational and rotational motions, the rovibrational Hamiltonian matrices are formulated for the rotational quantum numbers J = 0 and J = 1. The rovibrational Hamiltonian matrices are constructed and diagonalized using a Python program developed by the authors. Suitable algorithms for (i) the construction of one-dimensional cuts of potential energy surfaces along the pseudorotation angle ϕ and (ii) the assignment of the vibrorotational wave functions (which are needed for the automatic calculation of rotational transition energies J = 0 → J = 1) are described and discussed.

Characterizing the lone pair⋯π–hole interaction in complexes of ammonia with perfluorinated arenes

Stronger and more flexible lone pair⋯π–hole interaction of ammonia with respect to water in complexes with perfluorinated arenes.

Microbiologic Proof-Of-Concept: A Novel Device Combining UV Light And Ozone For Human Skin Antisepsis

Introduction/Objective

Hand hygiene (HH) decreases healthcare-associated infections (HAI). Available products include alcohol-based gels, foams, wipes, and “gold-standard” hand-washing with soap and water. We tested an investigational device (HyLuxO3; GMI, LLC, patent pending) for antimicrobial effect (AME). HyLuxO3 was engineered to deliver UV-C light energy and high velocity O3 airflow to safely achieve human skin antisepsis within OSHA and EPA regulatory limits. Combined UV and O3 has yet to be evaluated for HH and may demonstrate synergistic AME.

Methods

HyLuxO3 was tested on LB agar to titrate device variables to ascertain intensities for optimal AME; later testing was performed on VITRO-SKIN (Florida Suncare Testing, Bunnell, FL), a human skin surrogate. ATCC strains of MRSA, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Candida albicans were used to test AME vs. vegetative microbes; Bacillus atrophaeus spores were used as a surrogate for C. difficile. Tested variables included time under device, [O3], airflow velocity, 222 and/or 254 nm UV light, sample distance from UV lamp, and UV beam width. Positive controls were used to calculate log-kill curves for AME.

Results

Similar results were seen on LB agar and VITRO-SKIN. >7 log-kill and >5 log-kill were acheived vs. vegetative microbes (<30 sec) and spores (60 sec), respectively, under optimized variables. Presence of UV light and sample distance from and time under the device were the most important variables. 254 nm UV had a significantly better AME than 222 nm; combining both UV lamps had a significant synergistic AME. The narrowest UV beam (2 mm) yielded the greatest AME (total energy input kept constant). Adding O3 to UV had a modest but significant synergistic effect; optimal [O3] was 0.3-0.8 ppm. Changing airflow velocity had no significant effect on AME.

Conclusion

HyLuxO3 is a novel device that achieves >7 log-kill vs. common pathogenic vegetative microbes and >5 log-kill vs. spores using combined UV light and [O3] safe for human skin antisepsis (and surface/fomite decontamination)- and- yields such impressive AME on faster timescales than those required by bleach/other chemical products unsuitable for human skin. Future studies on human hands (using many other microbes) will determine if HyLuxO3 meets regulatory and efficacy requirements for use in and beyond healthcare settings, especially with the specter of emerging respiratory viruses.

Chlorination and tautomerism: a computational and UPS/XPS study of 2-hydroxypyridine ⇌ 2-pyridone equilibrium

The prototropic tautomeric equilibrium in 2-hydroxypyridine serves as a prototype model for the study of nucleobases' behaviour. The position of such an equilibrium in parent and chlorine monosubstituted 2-hydroxypyridine compounds in the gas phase was determined using synchrotron based techniques. The lactim tautomer is dominant for the 5- and 6-substituted compounds, whereas the parent, 3- and 4-substituted isomers have comparable populations for both tautomers. Information was obtained by measuring valence band and core level photoemission spectra at the chlorine L-edge and carbon, nitrogen, and oxygen K-edges. The effect of chlorine on the core ionization potentials of the atoms in the heterocycle was evaluated and reasonable agreement with a simple model was obtained. Basic considerations of resonance structures correctly predicts the tautomeric equilibrium for the 5- and 6-substituted compounds. The vibrationally resolved structure of the low energy portion of the valence band photoionization spectra is assigned based on quantum-chemical calculations of the neutral and charged species followed by simulation of the vibronic structure. It is shown that the first ionization occurs from a π orbital of similar shape for both tautomers. In addition, the highly distinctive vibronic structure observed just above the first ionization of the lactim, for three of the five species investigated, is assigned to the second ionization of the lactam.

Structure, Dynamics, and Accurate Laboratory Rotational Frequencies of the Acrylonitrile-Methanol Complex

The hydrogen-bonded complex between acrylonitrile (CH2═CHCN) and methanol has been characterized spectroscopically in the millimeter wave range (59.6-74.4 GHz) using a free jet absorption millimeter wave spectrometer. Precise values of the rotational and centrifugal distortion constants were obtained from the measured frequencies of the complex of acrylonitrile with CH3OH and CD3OD. The analysis of the splittings of the rotational lines due to the hindered internal rotation of the methanol methyl group led to the determination of a V3 value of 221.9(7) and 218(5) cm-1 for the complexes of CH3OH and CD3OD, respectively, and these values are about 40% lower than that of free methanol. The structure of the observed conformation is in agreement with the global minimum determined at the MP2/aug-cc-pVTZ level of calculation, and the counterpoise corrected intermolecular binding energy, obtained at the same theoretical level, is De = 26.3 kJ mol-1.

Terpenoids: shape and non-covalent interactions. The rotational spectrum of cis-verbenol and its 1 : 1 water complex

In isolated and mono-hydrated verbenol, as in simpler allyl alcohols, the conformational leading force is the OH⋯π interaction.

Non covalent interactions stabilizing the chiral dimer of CH2ClF: a rotational study

We report the rotational spectra of three isotopologues of the dimer of chlorofluoromethane, namely CH235ClF-CH235ClF, CH235ClF-CH237ClF and CH237ClF-CH235ClF. The assigned (most stable) conformer is chiral (C1 symmetry) and displays a network of two C-HCl-C and one C-HF-C weak hydrogen bonds, combined with a ClF halogen bond. The hyperfine structures due to the quadrupolar effects of the two non-equivalent 35Cl (or 37Cl) atoms have been fully resolved, leading to an accurate determination of two sets of diagonal and of some mixed quadrupole coupling constants. Information on the rs positions of the two Cl atoms and on the structural parameters of the hydrogen bonds has been obtained. The dissociation energy of the complex has been estimated as 5.9 kJ mol-1.

Atmospherically relevant acrolein–water complexes: spectroscopic evidence of aldehyde hydration and oxygen atom exchange

Rotational spectroscopy and isotopic studies evidence oxygen exchange in water complexes of atmospherically important acrolein.

Shapes, Dynamics, and Stability of β-Ionone and Its Two Mutants Evidenced by High-Resolution Spectroscopy in the Gas Phase

The conformational landscapes of β-ionone and two mutants (α-ionone and β-damascone) have been analyzed by means of state-of-the-art rotational spectroscopy and quantum-chemical calculations. The experiments performed at high resolution and sensitivity have provided a deep insight into their conformational spaces, assigning more than 8000 transitions corresponding to the rotational structures of 54 different species (3 isomers, 14 conformers, and 40 isotopologues). Methyl internal rotation dynamics were also observed and analyzed. The work proved the great flexibility of β-ionone due to its flatter potential energy surface. This feature confers on β-ionone a wider ability to interconvert between conformers with rather similar energies with respect to its mutants, allowing the retinal ligand to better adapt inside the binding pocket.

Rotational Spectrum and Conformational Analysis of N-Methyl-2-Aminoethanol: Insights into the Shape of Adrenergic Neurotransmitters

We describe an experimental and quantum chemical study for the accurate determination of the conformational space of small molecular systems governed by intramolecular non-covalent interactions. The model systems investigated belong to the biological relevant aminoalcohol's family, and include 2-amino-1-phenylethanol, 2-methylamino-1-phenylethanol, noradrenaline, adrenaline 2-aminoethanol, and N-methyl-2-aminoethanol. For the latter molecule, the rotational spectrum in the 6–18 and 59.6–74.4 GHz ranges was recorded in the isolated conditions of a free jet expansion. Based on the analysis of the rotational spectra, two different conformational species and 11 isotopologues were observed and their spectroscopic constants, including ¹⁴N-nuclear hyperfine coupling constants and methyl internal rotation barriers, were determined. From the experimental data a structural determination was performed, which was also used to benchmark accurate quantum chemical calculations on the whole conformational space. Atom in molecules and non-covalent interactions theories allowed the characterization of the position of the intramolecular non-covalent interactions and the energies involved, highlighting the subtle balance responsible of the stabilization of all the molecular systems.

Quantum Effects for a Proton in a Low-Barrier, Double-Well Potential: Core Level Photoemission Spectroscopy of Acetylacetone

We have performed core level photoemission spectroscopy of gaseous acetylacetone, its fully deuterated form, and two derivatives, benzoylacetone and dibenzoylmethane. These molecules show intramolecular hydrogen bonds, with a proton located in a double-well potential, whose barrier height is different for the three compounds. This has allowed us to examine the effect of the double-well potential on photoemission spectra. Two distinct O 1s core hole peaks are observed, previously assigned to two chemical states of oxygen. We provide an alternative assignment of the double-peak structure of O 1s spectra by taking full account of the extended nature of the wave function associated with the nuclear motion of the proton, the shape of the ground and final state potentials in which the proton is located, and the nonzero temperature of the samples. The peaks are explained in terms of an unusual Franck-Condon factor distribution.

Regarding the torsional flexibility of the dihydrolipoic acid's pharmacophore: 1,3-propanedithiol

The great flexibility of 1,3-propanedithiol is probed using freejet absorption microwave spectroscopy and quantum chemistry calculations.

Conformational Equilibrium and Internal Dynamics of E-Anethole: A Rotational Study

The rotational spectra of the two conformers of E-anethole have been investigated using the free jet broadband millimeter-wave spectroscopic technique combined with theoretical calculations. Anti and syn conformers differ for the relative orientation of the propenyl and methoxy chains, with all heavy atoms coplanar to the benzene ring. Relative intensity measurements prove that the anti form is the global minimum, about 2.0(5) kJ mol(-1) lower in energy with respect to the syn conformer, solving the contrasting results supplied by different theoretical methods. For both conformers, the barriers to internal rotation of the propenyl -CH3 group are low enough to generate fully resolved A-E splittings of the rotational transitions. The corresponding V3 barriers have been determined to be 7.080(5) and 6.978(4) kJ mol(-1), respectively.

Probing the Lone Pair···π-Hole Interaction in Perfluorinated Heteroaromatic Rings: The Rotational Spectrum of Pentafluoropyridine·Water

The rotational spectrum of the weakly bound complex pentafluoropyridine·water has been investigated with pulsed jet Fourier transform microwave spectroscopy. From the analysis of the rotational parameters of the parent species and of three water isotopologues, the structural arrangement of the adduct has been unambiguously established. The results show that the full ring fluorination of pyridine has a dramatic effect on its binding properties: It inverts the electron density distribution above the ring, creating a π-hole, with respect to the typical π-cloud of benzene and pyridine. In the complex the water moiety lies above the aromatic ring with the oxygen lone pairs pointing toward its center. This lone pair···π-hole interaction stabilizes the adduct, and it is more stable than the in-plane O-H···N hydrogen bond normally found in the complexes involving nitrogen heterocyclic aromatic rings. Evidence of a large amplitude motion involving the weakly bound water molecule has also been observed and discussed.

Persisting anorectal dysfunction after rectal cancer surgery

AIM

Sphincter-saving rectal cancer management affects anorectal function. This study evaluated persisting anorectal dysfunction and its impact on patients' well-being.

METHOD

Seventy-nine patients with a follow-up of 12-37 (median 22) months and 79 age- and sex-matched control subjects completed questionnaires.

RESULTS

The median number of diurnal bowel movements was three in patients and one in controls (P < 0.0001). Nocturnal defaecation occurred in 53% of patients. The median Vaizey score was 8 in patients and 4 in controls (P < 0.0001). Urgency without incontinence was reported by 47% of patients and 49% of controls (P = 0.873), soiling by 28% of patients and 3% of controls (P < 0.0001), incontinence for flatus by 73% of patients and 49% of controls (P = 0.0019), and incontinence for solid stools by 16% of patients and 4% of controls (P = 0.0153). Incontinence of liquid stools occurred in 17 of 20 patients and in one of five controls who had liquid stools (P = 0.0123). Incontinence for gas, liquid or solid stool occurred once or more weekly in 47%, 19% and 6% of patients respectively. Evacuation difficulties were reported by 98% of patients, but also by 77% of controls. Neoadjuvant radio(chemo)therapy adversely affected defaecation frequency and continence. Incontinence was associated with severe discomfort in 50% of patients, severe anxiety in 40% and severe embarrassment in 48%.

CONCLUSION

Anorectal dysfunction is a frequent problem after management of rectal cancer with an impact on the well-being of patients.

Treatment options to improve anorectal function following rectal resection: a systematic review

AIM

Common problems after rectal resection are loose stools, faecal incontinence, increased frequency and evacuation difficulties, for which there are various therapeutic options. A systematic review was conducted to assess the outcome of treatment options aimed to improve anorectal function after rectal surgery.

METHOD

Publications including a therapeutic approach to improve anorectal function after rectal surgery were searched using the following databases: MEDLINE, PubMed, EMBASE, Pedro, CINAHL, Web of Science, PsychInfo and the Cochrane Library. The focus was on outcome parameters of symptomatic improvement of faecal incontinence, evaluation of defaecation and quality of life.

RESULTS

The degree of agreement on eligibility and methodological quality between reviewers calculated with kappa was 0.85. Fifteen studies were included. Treatment options included pelvic floor re-education (n=7), colonic irrigation (n=2) and sacral nerve stimulation (SNS) (n=6). Nine studies reported reduced incontinence scores and a decreased number of incontinent episodes. In 10 studies an improvement in resting and squeeze pressure was observed after treatment with pelvic floor re-education or SNS. Three studies reported improved quality of life after pelvic floor re-education. Significant improvement of the Fecal Incontinence Quality of Life Scale was found in three studies after SNS.

CONCLUSION

Conservative therapies such as pelvic floor re-education and colonic irrigation can improve anorectal function. SNS might be an effective solution in selected patients. However, methodologically qualitative studies are limited and randomized controlled trials are needed to draw evidence-based conclusions.