Axial Phenoxylation of Aluminum Phthalocyanines for Improved Cannabinoid Sensitivity in OTFT Sensors

Cannabis producers, consumers, and regulators need fast, accurate, point-of-use sensors to detect Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) from both liquid and vapor source samples, and phthalocyanine-based organic thin-film transistors (OTFTs) provide a cost-effective solution. Chloro aluminum phthalocyanine (Cl-AlPc) has emerged as a promising material due to its unique coordinating interactions with cannabinoids, allowing for superior sensitivity. This work explores the molecular engineering of AlPc to tune and enhance these interactions, where a series of novel phenxoylated R-AlPcs are synthesized and integrated into OTFTs, which are then exposed to THC and CBD solution and vapor samples. While the R-AlPc substituted molecules have a comparable baseline device performance to Cl-AlPc, their new crystal structures and weakened intermolecular interactions increase sensitivity to THC. Grazing-incidence wide-angle X-ray scattering (GIWAXS) and atomic force microscopy (AFM) are used to investigate this film restructuring, where a significant shift in the crystal structure, grain size, and film roughness is detected for the R-AlPc molecules that do not occur with Cl-AlPc. This significant crystal reorganization and film restructuring are the driving force behind the improved sensitivity to cannabinoids relative to Cl-AlPc and demonstrate that analyte-semiconductor interactions can be enhanced through chemical modification to create more responsive OTFT sensors.

The fascinating story of axial ligand dependent spectroscopy and redox-properties in iron(II) phthalocyanines

Iron phthalocyanines play crucial fundamental and applied roles ranging from bulk colorants to components of advanced materials. In this Frontier article, we discuss four aspects concerning the influence of the axial ligands on spectroscopic and redox properties of iron(II) phthalocyanines: (i) iron versus macrocycle oxidation cite as a function of Lever's EL parameter; (ii) energy of the metal-to-ligand charge-transfer transitions as a function of Lever's EL parameter; (iii) iron versus macrocycle reduction in iron(II) phthalocyanines; (iv) Mössbauer quadrupole splitting as a function of axial ligand binding through the prism of dz2 orbital population.

Novel decorated aluminium(iii) phthalocyanine complex with the application of MWCNTs on electrodes: electrochemical non-enzymatic oxidation and reduction of glucose and hydrogen peroxide

In this study, we performed the physicochemical and electrochemical characterization of a decorated macrocyclic aluminium(iii) phthalocyanine complex (AlTMQNCAPc). Subsequently, the AlTMQNCAPc@MWCNT/GC electrode was used for the electrochemical detection of glucose and hydrogen peroxide (H₂O₂) by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CA). Moreover, the limit of detection, linear range, and sensitivity for glucose and H₂O₂ were investigated (CV: 2.5 nM L^-1 and 25 nM L^-1, 50-500 μM, 0.052 and 0.072 μA μmol cm^-2; DPV: 3.1 nM L^-1 and 18 nM L^-1, 50-500 μM, 0.062 and 0.066 μA μmol cm^-2 and CA: 10 nM L^-1 and 20 nM L^-1, 50-500 μM, 0.098 and 0.07 μA μmol cm^-2, respectively). In addition, the AlTMQNCAPc@MWCNT/GC electrode showed good selectivity for the detection of glucose and H₂O₂ in the presence of common interfering substances, such as AA, DA, UA, glycine, l-cysteine, nitrite, Pb(ii), Cd(ii), Cu(ii), Co(ii), Hg(ii), Zn(ii), and glucose. For the detection of glucose and H₂O₂, the kinetic parameters, including the electron transfer coefficient and catalytic reaction rate constant, were also established. Finally, for usage in practical applications, the modified electrode was employed to achieve the quantitative detection of glucose and H₂O₂ in human urine and commercial samples of 3% H₂O₂, respectively.

Experimental and Theoretical Studies on Optical Properties of Tetra(Imidazole) of Palladium (II) Phthalocyanine

In this work, the optical properties of tetra(imidazole) of palladium phthalocyanine (PdPc(Im)₄) in solution form and thin films on glass and fluorine-doped tin oxide (FTO) substrates were investigated via the thermal evaporation technique. The optical band gap was evaluated by ultraviolet–visible spectroscopy (UV-Vis). The energy band gap values were determined based on the Tauc graph. In addition, time-dependent density functional theory (TD-DFT) was used to simulate the UV-Vis absorption spectrum of the (PdPc(Im)₄) molecule in the Dimethyl Sulfoxide (DMSO) solution phase. A good correlation was found between the DFT results and the experimental optical results. The band gap values between the experimental and DFT-simulated values are presented. The energy band gap of (PdPc(Im)₄) obtained from the DFT calculations showed that it can be efficiently regulated. Frontier molecular orbitals and molecular electrostatic potentials were also proposed in this work. The surface study of the layers deposited on FTO was considered by atomic force microscopy (AFM) and scanning electron microscopy (SEM), and the results demonstrated good homogeneity covering the entire surface. The SEM image showed a homogeneous distribution of the grains with some spherical or rod-shaped structures and no agglomeration structures. This work rendered a strategy for regulating the energy band gap and compared the experimental observations obtained with theoretical studies, which provides a fundamental insight into the optical band for optoelectronic and thin-film solar cells.

A New Way to Predict the Efficiency of Optical Limiters without Providing an Experiment: Processing of TDDFT Calculations for the Case of Pure Two-Photon Absorption

Laser-power-limiting devices play a predominant role in photonics because of their potential for protecting human eyes and optical devices that are sensitive to intense laser beams. This paper describes a new methodology for predicting the efficiency of optical limiting based on electric-field-induced changes in absorption spectra calculated with the TDDFT quantum-chemical method. Analytical equations are derived to evaluate the optical thresholds and speed of switching on, the dynamic range, and the degree of nonlinear attenuation of the radiation fluxes for the case of two-photon absorption. Thus, the researcher does not need to conduct costly experiments to evaluate the suitability of nonlinear absorbers for the creation of optical limiters. The possibility of developing a forecasting model is demonstrated by an example of a series of stable slipped-cofacial phthalocyanine J-type dimers, which were synthesized and investigated previously.

Synthesis, Structure, and UV–Vis Characterization of Antimony(III) Phthalocyanine: [(SbPc)2(Sb2I8)(SbBr3)]2

A new antimony(III)–phthalocyanine complex with the formula of [(SbPc)2(Sb2I8)(SbBr3)]2 has been obtained in the reaction of pure antimony powder with phthalonitrile under the oxidation conditions by iodine monobromide vapors. The complex crystallizes in the centrosymmetric space group of the triclinic system. Both independent (SbPc)+ units exhibit non-planar conformation, since the Sb(III) is larger than the equilibrium cavity size of the ring and cannot be accommodated without its expansion; thus, the metal protrudes out of the cavity, forming a saucer shape. The centrosymmetric anionic unit of the crystal consists of two (Sb2I8)2− interacted anionic units forming (Sb4I16)4− anionic complex that interacts with two SbBr3 molecules to form [Sb6I16Br6]4− anionic aggregate. Each [Sb6I16Br6]4− anionic aggregate is surrounded by four (SbPc)+ cations forming a supramolecular centrosymmetric (SbPc)4[Sb6I16Br6] complex. Translationally related (SbPc)4[Sb6I16Br6] molecules form a stacking structure along the [100] and [011] directions with N4–N4 distances of 3.55 and 3.53 Å, respectively, between the back-to-back-oriented saucer-shaped (SbPc)+ units. The interaction between the building units of the crystal was analyzed using the Hirshfeld surface and the analysis of the 2D fingerprint plots. The UV–Vis absorption spectra of crystal 1 were taken in CH2Cl2 and toluene solutions in the concentration range from 10−5 to 10−6 mol/L. No significant changes related to aggregation in solutions were observed. The Q-band in toluene solution is red shifted by ~15 nm in comparison to that in CH2Cl2 solution. Oxidation of (SbPc)4[Sb6I16Br6] yields SbVPc derivative. Both SbIII and SbV phthalocyanine derivatives absorb near infrared light (600–900 nm), which should be intriguing from the point of view of potential use as photosensitizers for PDT and as an infrared cut filter for plasma display and silicon photodiodes.

Tetra-substituted phthalocyanines bearing thiazolidine derivatives: synthesis, anticancer activity on different cancer cell lines, and molecular docking studies

In the first step, (4R)-2-(2-hydroxyphenyl)thiazolidine-4-carboxylic acid (c) and 2-(2-(3,4-dicyanophenoxy)phenyl)thiazolidine-4-carboxylic acid (1) were prepared. Then, the peripherally tetra-substituted metallophthalocyanines [ZnPc (2), CuPc (3), and CoPc (4)] were synthesized by using 1. The structures of the obtained compounds were characterized by common spectroscopic methods. Aggregation behaviors of the tetra-substituted metallophthalocyanines (2-4) were investigated by UV-Vis and fluorescence spectroscopy in the presence/absence of soft metal ions. The electronic spectra of the newly synthesized metallophthalocyanines [ZnPc (2), CuPc (3), and CoPc (4)] were analyzed by the Bayliss method. The fluorescence quantum yield of diamagnetic ZnPc (2) was obtained in DMSO at room temperature. Also, the anticancer activity of the newly synthesized metallophthalocyanine derivatives was studied on C6, DU-145, and WI-38 cell lines and investigated using six concentrations (3.125; 6.25; 12.5; 50; 75; 100 μg L^-1). The cell cycle and apoptosis analyses of CuPc (3) were performed. In addition, the chemical and biological activities of 2-(2-(3,4-dicyanophenoxy)phenyl)thiazolidine-4-carboxylic acid (1) and its novel type metallophthalocyanines [ZnPc (2), CuPc (3), and CoPc (4)] were compared with many parameters obtained from the Gaussian software and molecular docking methods.

Electrochemical sensor based on magnetic nanohybrids of multiple phthalocyanine doped ferrites/CMWCNTs for detection of rosmarinic acid

Ferrites have attracted considerable attention in biosensor developments owing to their favorable electrochemical and magnetic properties. Speedy and trace analysis can be succeeded by the sensors based on magnetic nanohybrids. In this work, we reported a novel method for one-step synthesis of magnetic ferrites composed of Fe and phthalocyanine. After hybridization with carbonylated multi wall carbon nanotubes, a sensor based on Fe3O4-Pc-CMWCNTs nanocomposites was fabricated for the detection of rosmarinic acid (RA), a bioactive phytochemical. The sensor can be constructed within 30s without any complicated process. A comparison of electrochemical activity between ZnFe2O4-Pc-CMWCNTs and Fe3O4-Pc-CMWCNTs nanohybrids also has been accomplished in this work. Compared with ZnFe2O4-Pc-CMWCNTs based on commonly used ferrites, Fe3O4-Pc-CMWCNTs/MGCE exhibited a higher catalytical ability for the detection of RA. The sensor modified with Fe3O4-Pc-CMWCNTs displayed a low LOD of 0.182 μM with a wide linear range from 0.2 to 400 μM, which was 30 times more sensitive than the one based on ZnFe2O4-Pc-CMWCNTs. The obtained sensor also owned an excellent selectivity, reproducibility, repeatability, and stability, which made it achieve the measurements in plant sample and human serum.

Bis-indole substituted phthalocyanines: Photophysical and photochemical properties

Tetra substituted peripheral and non-peripheral Zn(II) phthalocyanines were successfully synthesized employing 4-(bis(3-methyl-1H-indol-2-yl)methyl)phenol as a starting material. The structure of these synthesized compounds was confirmed using 1H NMR, [Formula: see text]C NMR, infrared (IR), UV-vis, and MALDI-TOF spectral data. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation) properties of all synthesized peripheral and non-peripheral compounds were investigated in order to determine the potential of these compounds for application in photodynamic therapy.

Supramolecular subphthalocyanine complexes-cellular uptake and phototoxicity

In this communication we report on the synthesis and application of axially functionalized boron-subphthalocyanines (SubPC) which are able to form host-guest complexes with cyclodextrins. Here, a tert-butylphenyl substituted SubPC was investigated concerning its complexation with β-cyclodextrin (β-CD) and a β-cyclodextrin polymer. NMR-titrations showed the formation of a 1 : 1 complex with β-CD. These assemblies were analyzed for their cellular distribution as well as their phototoxicity towards HeLa cells.

Electric-Field-Induced Second Harmonic Generation Nonlinear Optic Response of A4 β-Pyrrolic-Substituted ZnII Porphyrins: When Cubic Contributions Cannot Be Neglected

In this work, we have prepared a series of A₄ Zn^II porphyrins, carrying in the β-pyrrolic-position one or two π-delocalized ethynylphenyl moieties with a -NO₂ acceptor or a -NMe₂ donor pendant, and measured their second-order NLO response in CHCl₃ solution at 1907 nm via the electric-field-induced second harmonic generation (EFISH) technique. For some of these compounds, we have recorded an unexpected sign and/or absolute value of μβ₁₉₀₇. Since their sterically hindered A₄ structure should ensure the lack of significant aggregation processes in solution, we explain such anomalous EFISH results by invoking a non-negligible contribution of the electronic cubic term γ(-2ω; ω, ω, 0) to γ_EFISH, as supported by a qualitative evaluation of the third-order response through the measure of the cubic hyperpolarizability (γ_THG) and by computational evidence.

Thiazole-substituted non-symmetrical metallophthalocyanines: synthesis, characterization, electrochemical and heavy metal ion sensing properties

Novel non-symmetrical metallophthalocyanines with a thiazole functional group were prepared. Their redox properties and heavy metal ion sensing performances were fully investigated.

Functional chalcone-substituted tetrakis-metallophthalocyanines: Synthesis and spectroscopic characterization

In this study, a new phthalonitrile derivative, ( E)-4-(3-(3-(3-methoxyphenyl)acryloyl)phenoxy)phthalonitrile, and four peripherally ( E)-4-(3-(3-(3-methoxyphenyl)acryloyl)phenoxy) tetrasubstituted new Ni(II), Zn(II), Co(II), and Cu(II) phthalocyanine derivatives are synthesized and characterized. ( E)-4-(3-(3-(3-Methoxyphenyl)acryloyl)phenoxy)phthalonitrile is synthesized by heating ( E)-1-(3-hydroxyphenyl)-3-(3-methoxyphenyl)prop-2-en-1-one and 4-nitrophthalonitrile in the presence of K2CO3 in dry DMF at 60°C for 96 h. The metallophthalocyanines are prepared by cyclotetramerization of ( E)-4-(3-(3-(3-methoxyphenyl)acryloyl)phenoxy)phthalonitrile with NiCl2, Zn(CH3COO)2, CoCl2, and CuCl2 in n-pentanol in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene. Characterization of the new compounds is performed by means of IR, 1H NMR, 13C NMR, and mass and UV-Vis spectroscopy techniques.

Optoelectronic, femtosecond nonlinear optical properties and excited state dynamics of a triphenyl imidazole induced phthalocyanine derivative

A novel zinc phthalocyanine derivative [2(3), 9(10), 16(17), 23(24) tetrakis-4-((4-(1,4,5-triphenyl-1H-imidazol-2-yl)phenyl)ethynyl)phthalocyanine zinc(ii) (PBIPC)] was synthesized by incorporating a triphenyl imidazole moiety at its peripheral positions. The detailed mechanisms of absorption, emission, electrochemical, nonlinear optical (NLO) and photophysical (excited state dynamics) properties of PBIPC were explored. The absorption and emission properties of the compound were studied in different solvents. The incorporation of a triphenyl imidazole moiety at the peripheral position of the zinc phthalocyanine slightly broadened the Soret band. The emission studies revealed fluorescence quantum yields to be in the range of 0.11-0.22. The time-resolved fluorescence data established the radiative lifetimes to be in the nanosecond range. The oxidation and reduction processes were found to be ring centered, which were studied using the cyclic voltammetry (CV) technique. The energy optimized structures and HOMO-LUMO levels were calculated using DFT, TD-DFT analysis and were employed by means of hybrid functional theory (B3LYP) at 6-31G (d,p) basis set in the Gaussian 09 package. Two-photon absorption was observed in the NLO studies performed in the visible wavelength range of 600-800 nm while the nonlinear absorption was dominated by three- and four-photon absorption processes in the NIR wavelength range (1.0-1.5 μm). The molecule exhibited self-focusing behavior for all the wavelengths. Finally, the excited state dynamics of the title molecule PBIPC were investigated using femtosecond transient absorption spectroscopy and the results obtained were understood on the basis of a simple three kinetic model, for excitation wavelengths of 400 nm (Soret band) and 650 nm (Q-band). Both the spectra demonstrated a broad positive transient absorption (TA) data which overlapped with the ground state bleach (GSB), which in turn displayed a red shift over a delay of ∼2 ns. The lifetimes revealed a possibility of intersystem crossing (τ > 1 ns) owing to the triplet state transition.

Template-controlled on-surface synthesis of a lanthanide supernaphthalocyanine and its open-chain polycyanine counterpart

Phthalocyanines possess unique optical and electronic properties and thus are widely used in (opto)electronic devices, coatings, photodynamic therapy, etc. Extension of their π-electron systems could produce molecular materials with red-shifted absorption for a broader range of applications. However, access to expanded phthalocyanine analogues with more than four isoindoline units is challenging due to the limited synthetic possibilities. Here, we report the controlled on-surface synthesis of a gadolinium-supernaphthalocyanine macrocycle and its open-chain counterpart poly(benzodiiminoisoindoline) on a silver surface from a naphthalene dicarbonitrile precursor. Their formation is controlled by the on-surface high-dilution principle and steered by different metal templates, i.e., gadolinium atoms and the bare silver surface, which also act as oligomerization catalysts. By using scanning tunneling microscopy, photoemission spectroscopy, and density functional theory calculations, the chemical structures along with the mechanical and electronic properties of these phthalocyanine analogues with extended π-conjugation are investigated in detail.

Extending the π‐conjugation of phthalocyanine dyes, while synthetically challenging, has the potential to produce desirable new molecular materials. Here, the authors use a templated on‐surface approach to synthesize several extended phthalocyanine derivatives from the same building block, including a lanthanide superphthalocyanine and an open‐chain polycyanine.