Naphthalocyanine-Based NIR Organic Photodiode: Understanding the Role of Different Types of Fullerenes.

In this work, we presented experimental observation on solution-processed bulk heterojunction organic photodiode using vanadyl 2,11,20,29-tetra tert-butyl 2,3 naphthalocyanine (VTTBNc) as a p-type material. VTTBNc is blended with two different acceptors, which are PC61BM and PC71BM, to offer further understanding in evaluating the performance in organic photodiode (OPD). The blend film of VTTBNc:PC71BM with a volumetric ratio of 1:1 exhibits optimized performance in the VTTBNc blend structure with 2.31 × 109 Jones detectivity and 26.11 mA/W responsivity at a -1 V bias. The response and recovery time of VTTBNc:PC71BM were recorded as 241 ms and 310 ms, respectively. The light absorption measurement demonstrated that VTTBNc could extend the light absorption to the near-infrared (NIR) region. The detail of the enhancement of the performance by adding VTTBNc to the blend was further explained in the discussion section.

Preparation of multifunctional long-persistent photoluminescence cellulose fibres.

Simple preparation of flame-retardant, photoluminescent, and superhydrophobic smart nanocomposite coating was developed and applied onto cotton fibres using the simple pad-dry-cure technique. This novel strategy involved the immobilization of rare-earth-doped aluminium strontium oxide (ASO; SrAl2 O4 :Eu+2 ,Dy+3 ) nanoparticles, environmentally friendly room temperature vulcanizing silicone rubber (RTV) and environmentally friendly Exolet AP422 (Ex). The fabrics were also able to produce a char film in the fire-resistant assessment, providing fibres with a self-extinguishing characteristic. Furthermore, the fire-retardant performance of the coated cotton samples remained resistant to washing over 35 laundry cycles. The superhydrophobicity of the treated fabrics was monitored to improve by increasing the photoluminescent phosphor nanoparticles. The produced transparent photoluminescent film displayed an absorption at 360 nm and an emission at 526 nm. The photoluminescent fabrics were observed to generate different colorimetric shades, including white, green-yellow and bright white as monitored by Commission Internationale de l'Éclairage laboratory colorimetric coordinates. Slow emissions were detected for the treated cotton fabrics as monitored by emission, ultraviolet-visible light absorption, lifetime, and decay time spectral profiles to indicate glow in the dark phosphorescence effect. Both comfort and mechanical properties of the coated fibres were evaluated by measuring their bending length and air permeability.

Synthesis and characterization of new thiazole-based Co(II) and Cu(II) complexes; therapeutic function of thiazole towards COVID-19 in comparing to current antivirals in treatment protocol.

Two thiazole-based complexes were prepared from Co(II) and Cu(II) ions. The new ligand and its complexes were fully characterized by analytical and spectral techniques. The ligand behaved as a neutral tridentate in its keto-form towards the metals via O(8), O(10) and O(18) atoms. This was suggested based on the lower shift of υ(CH[bond, double bond]O), υ(C[bond, double bond]O)amide and υ(C-O) vibrations. The electronic transitions in Co(II)-HL and Cu(II)-HL complexes displayed d-d- transitions which belong to 4T1g→4A2g(F) & 4T1g(F)→4T1g (P) and 2Eg →2T2g, in the two complexes, respectively. ESR spectrum of Cu(II)-HL complex displayed g-factor by the following order; g//(2.1740)>g⊥(2.0935)>2.0023, which agrees with octahedral geometry. The geometry optimization was executed by DFT/B3LYP method under valence double zeta polarized basis set (6-31G*), to confirm the structural forms and the mode of bonding. The orientation and the charges of O(8), O(10) and O(18) atoms, support the coordination of the ligand in its keto-form with the metal ions. Pharmacophore profiles were obtained regarding thiazole ligand and other recommended drugs (arbidol, avigan and idoxuridine) that used in treatment protocol of COVID-19 pandemic. Also, query was run in MolPort-library to obtain antiviral analogues, to broaden the search for an effective treatment. Three analogues were obtained for arbidol, avigan and idoxuridine drugs, which have the following numbers; MolPort-047-605-644, MolPort-004-768-508 and MolPort-028-750-709, respectively. Moreover, molecular docking was carried out to obtain all interaction details and rank the efficiency of thiazole compound versus the three antivirals in their interaction with the two COVID-19 proteins. The outcomes suggested the significant antiviral activity of idoxuridine and thiazole (enol-form), which not reach to eliminate the pandemic exactly. While, arbidol and avigan did not have an effective antiviral role, although they still used in COVID-19 treatment protocol.

Luminescence feature of new 3,6-di(thiazolidin-5-one-2-yl)-carbazole derivative: synthesis, photophysical properties, density functional theory studies, and crystal shape effect.

A new carbazole chromophore conjugated with substituted thiazolidine-4-one (CzPT) was synthesized by applying the Knoevenagel reaction between 3,6-diformyl-N-hexylcarbazole and ethyl 2-aceto-2-(5-oxo-3-phenylthiazolidin-2-ylidene)acetate. The chemical structure of the new derivative (CzPT) was elucidated by spectral studies. The CzPT absorption spectra in different solvents exhibited a red shift for λmax by increasing solvent polarity. Bands at 430-474 nm appeared and were attributed to intramolecular charge transfer with high π-π* characteristics. CzPT fluorescence spectra exhibited a red shift after increasing the solvent polarity. To understand the Stokes' shift ( ∆ ν ¯ ) behaviour of the CzPT derivative referring to the polarity of solvents, Lippert-Mataga and linear solvation-energy relationship (LSER) models were employed in which the LSER exhibited respectable results compared with Lippert-Mataga (r2 = 0.9707). Moreover, time-dependent density functional theory absorption spectra in hexane and dimethylformamide showed that λmax had a major contribution in the highest occupied molecular orbital to lowest unoccupied molecular orbital transition in both solvents. In addition, the reduced uniformity of crystal features may lead to dislocation or anomalous arrangement of crystals with irregular spacing, which automatically enhances the optical properties of such crystals.

Wide bandgap semiconductor-based novel nanohybrid for potential antibacterial activity: ultrafast spectroscopy and computational studies.

The properties of nanomaterials generated by external stimuli are considered an innovative and promising replacement for the annihilation of bacterial infectious diseases. The present study demonstrates the possibility of getting the antibiotic-like drug action from our newly synthesized nanohybrid (NH), which consists of norfloxacin (NF) as the photosensitive material covalently attached to the ZnO nanoparticle (NP). The synthesized NH has been characterized using various microscopic and spectroscopic techniques. Steady state fluorescence and time-correlated single photon counting (TCSPC)-based spectroscopic studies demonstrate the efficient electron transfer from NF to ZnO. This enhances the reactive oxygen species (ROS) production capability of the system. First principles density functional theory has been calculated to gain insight into the charge separation mechanism. To explore the electron densities of the occupied and unoccupied levels of NH, we have verified the nature of the electronic structure. It is observed that there is a very high possibility of electron transfer from NF to ZnO in the NH system, which validates the experimental findings. Finally, the efficacy of NH compared to NF and ZnO has been estimated on the in vitro culture of E. coli bacteria. We have obtained a significant reduction in the bacterial viability by NH with respect to control in the presence of light. These results suggest that the synthesized NH could be a potential candidate in the new generation alternative antibacterial drugs. Overall, the study depicts a detailed physical insight for nanohybrid systems that can be beneficial for manifold application purposes.

Antitumor activity of pyrrolizines and their Cu(II) complexes: Design, synthesis and cytotoxic screening with potential apoptosis-inducing activity.

Two novel series including Schiff bases of the pyrrolizine-5-carboxamides and their Cu(II) complexes were designed, synthesized and analysed using spectral and analytical techniques. The analytical results indicated the formation of the complexes in 1:1 or 1:2 (Metal:Ligand) ratio. The geometry around the Cu centers was confirmed to be tetrahedral or octahedral. The cytotoxic activity of the new compounds was evaluated using MCF-7 (human breast adenocarcinoma), A2780 (human ovary adenocarcinoma) and HT29 (human colon adenocarcinoma), in addition to MRC5 (normal human fetal lung fibroblast) cells using the MTT cytotoxicity assay. The Schiff base 12c and the Cu complex 13b were the most active in the two series with IC50 values in the range of 0.14-2.54 µM against the three cell lines. Also, the Cu complex 13e showed excellent activity against HT29 with IC50 = 0.05µM. 7-Cyano-N-(4-methoxyphenyl)-6-((3-phenylallylidene) amino)-2,3-dihydro-1H-pyrrolizine-5-carboxamide (12c) showed high selectivity (6-13 folds) for cancerous cells over normal cells; and it induced marginal increases in the G1 and S phases of MCF-7 cells during cell cycle analysis, while compound 13b increased the MCF-7 Sub-G1 proapoptotic population, and blocked cells in the G2-M phase in a dose dependent manner. The annexin V apoptosis assay revealed the ability of compounds 12c and 13b to increase the early apoptotic MCF-7 cell populations two and three fold, respectively. Furthermore, these findings were supported by data showing that the two compounds (12c and 13b) elicit cytotoxic activity. Taken together, the data presented in this study warrants further in vitro and in vivo investigations.

Compositional engineering of VOPcPhO-TiO2 nano-composite to reduce the absolute threshold value of humidity sensors.

This research work demonstrates compositional engineering of an organic-inorganic hybrid nano-composites for modifying absolute threshold of humidity sensors. Vanadyl-2,9,16,23-tetraphenoxy-29H,31H-phthalocyanine (VOPcPhO), an organic semiconductor, doped with Titanium-dioxide nanoparticles (TiO2 NPs) has been employed to fabricate humidity sensors. The morphology of the VOPcPhO:TiO2 nano-composite films has been analyzed by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). The sensors have been examined over a wide range of relative humidity i.e. 20-99% RH. The sensor with TiO2 (90nm) shows reduced sensitivity-threshold and improved linearity. The VOPcPhO:TiO2 (90nm) nano-composite film is comprised of uniformly distributed voids which makes the surface more favorable for adsorption of moisture content from environment. The VOPcPhO:TiO2 nano-composite based sensor demonstrates remarkable improvement in the sensing parameter when equated with VOPcPhO sensors.

Co/Cr-Decorated Carbon Nanofibers as Novel and Efficacious Electrocatalyst for Ethanol Oxidation in Alkaline Medium.

In this work, Co/Cr nanoparticles-decorated carbon nanofibers were studied as a platinum-free catalyst for electrooxidation of ethanol in the alkaline medium. The investigated nano composites were prepared by simple, high yield and effective technique; electrospinning of cobalt acetate, chromium acetate and polyvinyl alcohol as a polymer precursor at 20 kV followed by calcination under inert atmosphere at 900 °C for 2 h. The suitable physicochemical characterizations such as XRD, SEM, TEM, TEM mapping, Line TEM-EDX and FE-SEM indicated the formation of pure CoCr nanoparticles allocated in/on carbon nanofibers. Electro catalytic activity measurements showed that the investigated Co­Cr carbon nanofibers can be effectively utilized in ethanol electrooxidation in 1 mol/l KOH solution. The observed current density was 105 mA/cm2 which is considered high value for non-precious electrocatalyst. Also, study the influence of Cr content in Cr­Co alloy toward ethanol oxidation was investigated to obtain the most effective composition. The suitable Cr concentration found to be 10% of Co content.

Visualisation of electrochemical processes at optically transparent carbon nanotube ultramicroelectrodes (OT-CNT-UMEs).

Optically transparent ultramicroelectrodes (OT-UMEs) comprising carbon nanotube (CNT) networks on quartz, are introduced and used to monitor quantitatively the interfacial concentration of tris(2,2'-bipyridine)ruthenium(II) during cyclic voltammetry. The OT-CNT-UMEs combine the attractive properties of small-scale electrodes, e.g., high diffusion rates and good signal-to-noise, with the ability to probe electrochemical processes optically, from the rear of the electrode. This enables optical measurements of the solution, close to the electrode surface, without significant interference from absorption or scattering processes.