The Performance Evaluation of Meso-Tetraphenyl Porphyrin and Azo Dyes as Photosensitizers in Dye-sensitized Solar Cells.

The photovoltaic properties of five different mono-azo function and meso-tetraphenyl porphyrin dyes have been investigated by computational DFT/TDDFT calculations and measurement of the J-V properties of their cells. The photovoltaic efficiency of the cells based on these dyes were determined by both experimental and theoretical methods. The efficiency-to-cost ratios of the azo-dye cells showed that they could be cheaper substitutes to porphyrin-based cells. Eriochrome blue black (EBB) and eriochrome black T (EBT) cells were shown to possess the best photovoltaic properties by the two methods employed (theory and experiment). The presence of two naphthol moieties at both ends of their -N = N- group has been adduced as possible reason for their relatively outstanding performance. The extremely low efficiency-to-cost ratio obtained for cell-POR suggests that the use of porphyrin as sensitizer may not be as economically viable as some azo dyes. MTO, EBB and EBT were found to be the most cost-effective among the investigated dyes. The porphyrin's low performance may have been amplified by the absence of an effective anchor group in its molecular structure.

A DFT Study of Solvent and Substituent Effects on the Adsorptive and Photovoltaic Properties of Some Selected Porphyrin Derivatives for DSSC Application.

A DFT/TD-DFT method was employed to study the effects of structural modification and solvent variation on the solubility, adsorptive, and photovoltaic properties of six porphyrins (A-F) obtained by structurally modifying two literature porphyrins A and D. The properties of interest were studied in vacuum, acetonitrile (AcCN), dichloromethane (DCM), dimethyl sulphoxide (DMSO), and ethanol (EtOH) for possible application of the molecules as sensitizers in dye-sensitized solar cells (DSSCs). Electronic absorption properties of the molecules were computed via potential energy surface scan, and thermodynamic data were obtained by DFT calculations in the selected media. Solubility properties of the molecules were mostly enhanced with DMSO as the solvent. The adsorptivity of the molecules onto mesoporous titanium (IV) oxide surface were predicted to be enhanced in the presence of DMSO. Most of the molecules were found to exhibit their highest photovoltaic activity measured in terms of the incident photon conversion efficiency (IPCE) in AcCN and DCM, rather than in DMSO due to its high viscosity and the ability to use its oxygen to form the catenating O-Ti4+ bond with the Ti4+ of the TiO2, causing inhibition of electron movement on the semiconductor surface. In general, the computed photovoltaic (PV) properties were found to be enhanced with -CO2H group as the substituent, and in AcCN or DCM as the solvent.

I-V Curves of an Apigenin Dye and Their Analysis by a New Parabolic Function.

A new parabolic function for I-V curves' analysis has been proposed. The new "analytical tool" provides a simple way to describe photophysical processes at an approximately monolayer surface of a dye-sensitized solar cell. It may now be possible to estimate factors such as hole-electron recombination, surface defects, and electron diffusion at the semiconductor layer. The theoretical approach that was previously reported by our group for predicting the photovoltaic performance of potential dye sensitizers has also been validated. The experimental photovoltaic and DFT/TD-DFT data of apigenin and those of the highly rated black dyes were used for the validation.

Tryptanthrin from microwave-assisted reduction of isatin using solid-state-supported sodium borohydride: DFT calculations, molecular docking and evaluation of its analgesic and anti-inflammatory activity.

Tryptanthrin is a potent natural alkaloid with good in vitro pharmacological properties. Herein, we report the synthesis of the compound via a new method involving the reduction of isatin with solid-state-supported sodium borohydride under microwave irradiation. The title compound has been tested for its analgesic and anti-inflammatory activity. The results showed that tryptanthrin dose dependently inhibits oedema and pain formation in all the models used. The agent also exhibited significant higher effects in its anti-inflammatory and analgesic activities better than positive drugs (aspirin and indomethacin) being currently used in the treatment and in the management of acute and chronic forms of pain and inflammatory disorders. The inhibitory potential of the compound was investigated by molecular docking using the software AutoDock Vina. The docking results were used to better rationalize the action and prediction of the binding affinity of tryptanthrin. Density Functional Theory (DFT) calculations at the B3LYP/6-311++G (2df, 2pd) level of theory showed that compared to ascorbic acid, tryptanthrin shows higher antioxidant activity which may be improved upon by functionalizing the aromatic core to enhance its solubility in polar solvents. The calculated electronic and thermodynamic properties obtained for tryptanthrin compete well with the standard ascorbic acid.

Supramolecular architecture in 1:1 cocrystal of N-carbamothioylacetamide and N,N'-thiocarbonyldiacetamide from the attempted synthesis of 1,3-diacetyl-2-thioxoimidazolidine-4,5-dione (a thioparabanic acid derivative).

An attempt to synthesize thioparabanic acid as precursor to other fused heterocyclic compounds, by a microwave assisted multistep one-pot reaction yielded a co-crystal of N-carbamothioylacetamide (NCTA) and N,N'-thiocarbonyldiacetamide (NNTCA) which is being reported in this paper. The structure of N-carbamothioylacetamide and N,N'-thiocarbonyldiacetamide from the attempted synthesis of 1,3-diacetyl-2-thioxoimidazolidine-4,5-dione, C5H8N2O2S.C3H6N2OS, has triclinic (P-1) symmetry. It is of interest with respect to biological application. The structure displays inter- and intra-molecular hydrogen bonding through -C=O···H interactions. Similarly, -C=S···H hydrogen bonding interactions are present, providing additional intermolecular stability to the co-crystal. For application as a potential drug candidate, a density functional theory (DFT) simulation of the antioxidant activities of the co-crystal and its individual components (NCTA and NNTCA) has been performed. The computed redox potentials indicate that the study compounds show comparable antioxidant activities with ascorbic acid (AA) for a one electron transfer process. Meanwhile, for a two-electron process, AA showed significant antioxidant advantage over the titled compound.

Anticancer Activity Study and Density Functional/Time-Dependent Density Functional Theory (DFT/TD-DFT) Calculations of 2(3),9(10),16(17),23(24)-Tetrakis-(6-Methylpyridin-2-Yloxy)Phthalocyaninato Zn(II).

Photodynamic therapy (PDT) is one of the major therapeutic methods for the treatment of infectious diseases and cancer. Recently, cell culture has been used to determine the effect of a given substance on various pathological conditions, such as cancer. In this study, we aimed to investigate the effect of a Zn- phthalocyanine (ZnPc) derivative on selected cancer cells via a cell culture medium. Methylthiazole tetrazolium (MTT) assay was applied to evaluate the cytotoxic activity of 2(3),9(10),16(17),23(24)-tetrakis-(6-methylpyridin-2-yloxy)phthalocyaninato Zn(II) on rat glioma cells (C6 glioma), human lung cancer cells (H1299) and human umbilical vein endothelial cells (HUVEC). The levels of the lipid peroxidation were determined by measuring the amount of the thiobarbituric acid reactive substance (TBARS) produced using the TBARS assay. The relationship between the oxidative damage and the effective concentration of cytotoxic ZnPc was determined from the results. The apoptotic and genotoxic effects of the phthalocyanine (Pc) were also investigated. Density functional/time-dependent density functional theory (DFT/TD-DFT) methods were used to determine the molecular excited state properties of the ZnPc and chloroaluminum phthalocyanine (ClAlPc) previously reported by Castilho-Fernandes et al. The computed and experimental data were used to establish a link between the electronic and anticancer properties of the Pcs.

Optical limiting properties of 3,5-dipyrenylvinyleneBODIPY dyes at 532nm.

The optical limiting (OL) properties of 3,5-dipyrenylvinyleneBODIPY dyes that contain both electron withdrawing and donating moieties have been investigated by using the z-scan technique at 532nm in the nanosecond pulse range. The extension of the π-conjugation at the 3,5-positions with pyrenylvinylene groups results in a ca. 200nm red shift of the main BODIPY spectral band to ca. 700nm, so there is relatively weak absorbance at 532nm under ambient light conditions. Reverse saturable absorbance (RSA) profiles are observed in response to incident pulsed laser light that is consistent with a two photon absorption-assisted excited state absorption (ESA) mechanism in CH2Cl2 solution and when the dyes are embedded in poly(bisphenol carbonate A) (PBC) polymer thin films. This demonstrates that 3,5-divinyleneBODIPY dyes are potentially suitable for use in OL applications, since limiting threshold fluence (Ilim) values of below 0.95Jcm-2 are observed when thin films are prepared.

Optical nonlinearities in non-peripherally substituted pyridyloxy phthalocyanines: a combined effect of symmetry, ring-strain and demetallation.

The optical nonlinearities of six non-peripherally-substituted pyridyloxy phthalocyanines have been studied at 532 nm using a nanosecond Z-scan technique in a dimethyl sulphoxide solution. Ring-strain effects and the absence of a metal center were found to greatly reduce the inherent high nonlinearities expected of some of these phthalocyanine complexes. Of the six molecules investigated, 1(4),8(11),15(18),22(25)-tetrakis-(2-pyridyloxy)phthalocyaninato lead(II) 3, 1(4),8(11),15(18),22(25)-tetrakis-(2-pyridyloxy)phthalocyanine 5, and 1(4),8(11),15(18),22(25)-tetrakis-(4-pyridyloxy)phthalocyanine 6 were found to exhibit negligible nonlinear optical behavior, due to either the absence of asymmetry or central metal and/or the presence of a ring-strain effect. A two-photon absorption process was found to be the major contributor to the observed reverse saturable absorption (RSA) in 1(4),8(11),15(18),22(25)-tetrakis-(4-pyridyloxy)phthalocyaninato lead(II) 4, 1(4)-mono-(2-pyridyloxy)phthalocyaninato lead(II) 7, and 1(4)-mono-(4-pyridyloxy)phthalocyaninato lead(II) 8, with large two-photon absorption cross-section, high hyperpolarizability and high third-order susceptibility values in the range of 4.53 × 10(-43)-5.33 × 10(-42) cm(4) s per photon, 1.61 × 10(-28)-1.89 × 10(-27) esu and 9.73 × 10(-12)-7.05 × 10(-11) esu respectively.