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This work deals with the synthesis and characterization of ionic liquid 1-Propyronitrile-3-Butylimidazolium Dicyanamide [C 2 CNBIM][N(CN) 2 ], followed by the experimental investigations on the density, refractive index, and dynamic viscosity of 1-Propyronitrile-3-Butylimidazolium Dicyanamide ionic liquids (IL) within the temperature range of 293.15 K to 353.15 K. The results revealed that the density decreased from 1.1197 g/cm3 to 1.0940 g/cm3 with the rise in temperature due to the increase in volume as a result in an increase in the intermolecular distance. The refractive index was found to be reduced from 1.5195 to 1.5061 alongside temperature increments due to the compact groups of molecules being demolished following the increased intermolecular distance. The dynamic viscosity found to be reduced from 276.26 mPa·s to 15.896 mPa·s with an increase in temperature because of weakened van der Walls forces compared to the hydrogen bonding with rising temperature and kinetic energies. Furthermore, ten different generalised models were applied for density prediction, exhibiting the minimum possible standard deviation of 0.0089. To improve the prediction ability, group contribution method-based models were developed for the density, refractive index, and dynamic viscosity prediction, resulting in the optimum values of standard deviation, average absolute relative deviation (AARD%), and correlation coefficient of 0.0081, 0.45%, and 0.9145, respectively. The developed models demonstrated a good agreement with the experimental data and previously reported models. Therefore, the proposed models are believed to be adequately precise for engineering calculations. Unlabelled Image • An ionic liquid [C 2 CNBIM][N(CN) 2 ] synthesised and characterized • Density, refractive index, and dynamic viscosity measured experimentally • Negative influence of temperature on physical properties was observed. • Proposed models are believed to be precise enough for engineering calculations. [ABSTRACT FROM AUTHOR]

• DFT and molecular dynamic studies of liver cirrhosis biomarker volatiles. • PTN_Ga@AlNNT and LMN_Ga@AlNNT possessed the highest and least energy gap. • PTN_Ga@AlNNT have the highest fraction of electronic transfer for the studied systems. • In@ AINNT have the highest stabilization energy. • Molecular dynamic show that the nanomaterials induced conformational changes. In the realm of scientific curiosity, the quest to develop groundbreaking biosensor technology and materials that cater to the urgent societal demands in healthcare, environment, food safety, and beyond has reached unprecedented heights. In this study, we delve into the captivating world of cutting-edge research, harnessing the power of density functional theory (DFT) at the B3LYP-GD3(BJ)/def2-SVP level of theory to investigate the adsorption, conductivity, reactivity, and dynamical stability of biomarker volatiles of liver cirrhosis: limonene (LMN), methanol (MTN), and pentanone (PTN) on aluminum nitride nanotube (AlNNT) and its metals doped Indium (In) and Gallium (Ga) designed surfaces. From the evolution in band gap analysis, PTN_Ga@AlNNT was noticed to have obtained least energy gap of 3.035 eV whereas, LMN_Ga@AlNNT system had the highest energy gap of 4.330 eV. The calculated fraction of electronic transfer for the studied systems were observed as thus; −2.48936, −0.798342 and −6.321428571 for LMN_Ga@AlNNT, MTN_Ga@AlNNT and PTN_Ga@AlNNT respectively. The perturbation energy analysis presents an increasing stabilization energy of Aluminum nanotube doped with Gallium (Ga) and indium (In) surface to followed the trend; In@ AINNT > Ga@ AINNT. Results from the Molecular Dynamic simulation suggest that the nanomaterials studied induced conformational changes in all six complexes during the simulation, as evidenced by the changes in energy and temperature. Also, from the UV– Vis analysis, the excited states in all three instances are single-A states, which implies they have spin quantum number S = 0. We hope this research work will contribute to the development efficient biosensor materials. [ABSTRACT FROM AUTHOR]

The ligand structure and optimized calcination temperature and time of Zn-MOF produced carbon encapsulated ZnO nanostructure that showed excellent dye adsorption from water. [Display omitted] • Synthesis of nitrogen doped carbon encapsulated ZnO hybrid nanostructures from Zn-MOFs. • Optimizing the reaction condition and ligand structure for ZnO preparation. • Enhanced cationic dye adsorption by ZnO-NC hybrid nanostructures. • Removal of dyes by filtration through ZnO hybrid nanostructures as column packing materials. • Kinetics and adsorption isotherm models were evaluated. Water pollution by organic dyes poses great challenge to the environment as well as living organisms. Herein, we have fabricated nanoplates of ZnO in carbon matrix by controlled calcination of zinc-metal organic frameworks (Zn-MOFs) and used as adsorbents for efficient removal of organic dyes from water. Zn-MOF of phthalic acid and 5-nitrophthalic acid produced nanoplates of ZnO (ZnO-C and ZnO-NC) in carbon matrix without and with nitrogen doping. The fabricated hybrid nanostructures were characterized using PXRD, FTIR, BET, TGA, HR-SEM, HR-TEM and XPS analysis. Both ZnO-C and ZnO-NC showed high adsorption of cationic dyes (crystal violet (CV), methylene blue (MB) and Rhodamine B (Rh B)) compared to anionic dyes (methyl orange (MO) and Eosin yellow (EY)). Nitrogen doped ZnO-NC exhibited relatively higher percentage of dyes removal (99 %) compared to ZnO-C. Interestingly, ZnO-NC showed high adsorption of MB dye across the pH range from acidic (pH = 3.0) to alkaline (pH = 11.0). The zero-point charge indicated the negative surface charge for ZnO-NC/ZnO-C that facilitated electrostatic interactions between dyes and adsorbents. Adsorption kinetics suggested a pseudo second order model and adsorption isotherm fitted well with the Freundlich model, suggesting heterogenous adsorption with multilayer coverage of dye molecules. The reusability of ZnO-NC showed only slight reduction of adsorption in three successive cycles. Further, ZnO-NC was used as column packing materials for the successful removal of both cationic as well as anionic dyes upon filtration. Thus, the present studies provided insight on the organic ligand structure and calcination temperature of MOFs for transforming them into effective organic dye adsorbent. [ABSTRACT FROM AUTHOR]

Porous metal organic frameworks exhibited strongly enhanced highly selective cationic dyes adsorption upon coating with natural tea extract. [Display omitted] • Synthesis of porous ZnTPA MOFs nano/micro particles using amine as structure controlling agents. • Strong enhancement of ZnTPA MOF dye adsorption capability via coating natural biomolecules from tea extract. • ZnTPA MOFs with natural tea extract coating showed highly selective adsorption of cationic dyes. • Easy regeneration of exhausted MOFs and high retention of adsorbed dyes. A simple, sustainable method was developed for boosting the dye adsorption capability of porous metal organic frameworks (MOFs) by coating them with natural tea extract. Nano/microparticles of zinc-terephthalic acid (ZnTPA) MOFs exhibited only 40% rhodamine B (Rh B) dye adsorption. The dye adsorption capability was strongly enhanced (up to 95%) after coating with natural tea extract and highly selective cationic dye adsorption. The coating of multifunctional biomolecules onto the ZnTPA matrix was expected to facilitate strong intermolecular interaction between MOF surface and organic dyes, which contributed to strongly enhanced dye adsorption. ZnTPA/Tea MOFs not only exhibited enhanced dye adsorption but also showed high retention capability. The broader scope of tea extract coating methodology for cationic dye adsorption was also demonstrated using other MOFs matrix. The exhausted ZnTPA MOF was easily regenerated by sonication followed by re-dipping into tea extract. Tea extract coated ZnTPA MOFs was also used as column packing materials for removing cationic dyes by filtration. Thus, the present work reported a facile strategy for efficient cationic organic dyes removal from the aqueous medium. [ABSTRACT FROM AUTHOR]

• Thermo-physical characteristics of ILs-amine hybrid solvent were studied for CO 2 capture. • The CO 2 absorption tests were conducted in hybrid media at 30 °C and 2 bar to 50 bar. • The viscosity of the samples does not change over the temperature range from 25 to 70 °C. • The hybrid solvent containing 10 wt% [bmim][TfO] exhibited highest CO 2 absorption kinetics. The thermo-physical characteristics of an ionic liquid-amine hybrid solvent were studied in this work as a result of its potential use in the CO 2 absorption process. The hybrid solvents were developed by mixing 30 wt% MDEA with ionic liquid at different concentrations of 5 wt%, 10 wt%, 15 wt% and 20 wt%. Three imidazolium-based ILs were investigated: 1-butyl-3-methylimidazolium dicyanamide [bmim][DCA], 1-butyl-3-methylimidazolium acetate [bmim][Ac] and 1-butyl-3-methylimidazolium trifluoromethanesulfonate [bmim][TfO. Aqueous ionic liquid-amine hybrid solvent's density, surface tension, refractive index, viscosity and were studied between 25 °C and 70 °C with a regular interval of 5 °C. Whereas the influence of temperature on viscosity is negligible beyond 65 °C and the influence of temperature changed certain physicochemical properties. Furthermore, high-pressure solubility tests were conducted at a fixed temperature of 30 °C to determine the solubility of CO 2 in hybrid media at pressures ranging from 2 bar to 50 bar. The results showed that the CO 2 solubility of the different ionic liquid-amine hybrid systems decreases in the following sequence: [bmim][TfO] + MDEA > [bmim][DCA] + MDEA > [bmim][Ac] + MDEA. It was also found out that the optimum concentration of ionic liquids in the solution is 10 wt%. The kinetics study of the hybrid solvents was studied as a function of concentration, and experimentally determined that 10 wt% [bmim][TfO] exhibited the fast CO 2 absorption kinetics. The kinetics performance study was further conducted as a function of pressure, and the highest absorption rate was recorded at 50 bar as expected. Overall, the addition of ionic liquids was verified to improve the CO 2 absorption and thus it was reported that ionic liquid-amine hybrid solvent is an auspicious solvent for CO 2 removal in the future. [ABSTRACT FROM AUTHOR]

• Quantum chemical calculations on performed on few oxazole compounds using. • Band gap, local softness values have been procured for different solvents. • Chemical structure and reactivity, topological analyses were carried out. • Solvation effects on UV–Visible spectrum were inspected using the TD-DFT system. • Optical properties and charge transport nature of the compounds were explored. The ground state geometries of oxazole compounds, i.e. , 3,5-Bis-(4-chloro-phenyl)-7a-methyl-dihydro-oxazolo[3,4-c]oxazole (Compound 1) and 3,5-Bis-(4-methoxy-phenyl)-7a-methyl-dihydro-oxazolo[3,4-c]oxazole (Compound 2) were optimized using Density functional theory employing B3LYP/6-31G++ level for comparing the geometric parameters (torsion angles, bond angles & bond lengths) with the X-ray crystallographic information. We explored the charge transport nature, wave functional properties, optical and electronic properties of both the oxazoles. The computed geometric parameters are rational to the experimental data. The time-domain TD - B3LYP/6-31G++ & the B3LYP/6-31G++ levels were used to reveal the electronic characteristics and absorption wavelength. Intra-molecular charge transfer was perceived in studied compounds. The IEFPCM (Integral Equation Formalism Polarizable Continuum Model) model was used to calculate the solvation UV spectrum. The effect of various solvents (acetone, acetonitrile, DMF(Dimethylformamide), DMSO (Dimethyl sulfoxide) and methanol) was examined on the excitation energies but solvent polarity has no discernible impact on the wavelengths of absorption. From HOMO-LUMO (Highest Occupied Molecular Orbital – Lowest Unoccupied Molecular Orbital) orbitals with various solvent molecules, band gap energies with the solvation effect are determined. Additionally, through the use of topological analytics like RDG (Reduced Density Gradient), ELF (Electron Localisation Function) & LOL (Localised Orbital Locator), the energy concentration of electrons was elucidated. Furthermore, the outcome of electron-donating cluster (–OCH 3) and electron-withdrawing cluster (–Cl) was studied on open-circuit voltage, bandgap alignment, electron coupling constants, excitons dissociation values, ΔGinject – electron injection, LHE-Light Harvesting Efficiency and electron coupling constants (|V RP |). [ABSTRACT FROM AUTHOR]

Abstract Novel smart polystyrene-poly(N -isopropylmethacrylamide-acrylic acid) [PSt@p(NIPMAM-Aac] core/shell gel particles were prepared by two step precipitation polymerization method and used as adsorbent for removal of heavy metal ions such as Pb(II), Cu(II), Cd(II) and Cr(III) from aqueous medium. The adsorption capacity of gel particles for Pb(II), Cu(II), Cd(II) and Cr(III) ions was found as 555.6, 526.3, 476.2 and 434.8 mg/g, respectively. Adsorption process was also studied under different adsorption conditions such as adsorbent dose, metal ions concentration, agitation time, pH and temperature. Adsorption isotherms study was performed for heavy metal ions removal under optimum adsorption conditions. Langmuir and Freundlich adsorption isotherms were employed to evaluate the mechanism of adsorption process. Kinetic study showed the adsorption process followed pseudo second order kinetics. Thermodynamic study enlightens the nature of adsorption process on the basis of thermodynamic parameters such as standard Gibbs energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°). Fourier transform infrared (FTIR) spectroscopy was used to elucidate the characteristics of gel and metal ions loaded gel particles. pH sensitivity and size of gel particles were evaluated by dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. Recoverability and reusability of gel particles for Pb(II) ions removal were also studied to investigate the repeated usage of our reported adsorbent for removal of pollutants from aqueous medium. Graphical abstract Unlabelled Image Highlights • Core/shell polymer particles with narrow size distribution were successfully synthesized. • Core/shell microgel particles have excellent ability to extract heavy metals from aqueous medium. • Langmuir adsorption isotherm model best interprets the metal ions adsorption process. • The adsorbent system has high stability and recoverability and can be re-used. [ABSTRACT FROM AUTHOR]

Abstract Poly(N -isopropylmethacrylamide-acrylic acid) [pniM-Ac] microgel particles were synthesized by surfactant free radical precipitation polymerization method. Microgel particles were used as adsorbent for the removal of toxic dyes such as Congo red (CR) (anionic), methylene blue (MB) (cationic) and Rhodamine B (Rh-B) (cationic) from aqueous medium at ambient temperature. Due to presence of carboxylate groups inside the polymer chains of microgel particles, uptake of cationic dyes such as MB and Rh-B was high as compared to anionic dye CR at low temperature and high pH of the medium. But at high temperature, microgel particles were shrunken and their hydrophobicity was increased. Under such conditions, uptake of anionic dye CR was high due to increased hydrophobic interaction between polymer chains of microgel particles and dye molecules. Effect of dye concentration, adsorbent dose, pH of the medium and agitation time on the percentage removal of dyes was also investigated and their optimum values were determined. Langmuir isotherm model best explained the adsorption of CR, MB and Rh-B on microgel particles. Pseudo second order has well explained the kinetics of adsorption of all dyes on microgel system as compared to other kinetic models as reflected by the values of regression coefficients (R2). Mechanism of adsorption of all dyes on microgel particles was explained by intra-particle diffusion model. Microgel particles also showed high capacity to extract toxic dyes simultaneously from aqueous medium as compared to their individual adsorption. Pure and dye loaded microgel particles were analyzed by UV–visible (UV–vis) spectroscopy and Fourier transform infrared (FTIR) spectrometry. Size and morphology of microgel particles were investigated by transmission electron microscopy (TEM). Graphical abstract Unlabelled Image Highlights • Poly(N -isopropylmethacrylamide-acrylic acid) microgels were prepared by emulsion polymerization method. • Microgels are efficient adsorbents for the removal of toxic dyes from aqueous medium. • Adsorption of various dye molecules such as methylene blue, Rhodamine B and Congo red followed Langmuir adsorption model. • Kinetic study indicates that adsorption of dye molecules followed the pseudo second order. • Microgel particles showed recyclability and reusability for the removal of dye molecules from aqueous medium. [ABSTRACT FROM AUTHOR]

[Display omitted] • A hybrid computational approach consisting of different computational methods is used. • Molecular electronic structures, and therapeutic potential of piperidine compounds are tested against SARS-CoV-2. • The molecular docking and MD simulations results reveal the significant therapeutic potential of designed compounds. • The MMPBSA analysis indicate that all the complexes possess good binding free energy at binding site of receptor. • ADMET analysis reveals that all eight ligands are efficient drug candidates for Mpro of SARS-CoV-2. In the current study, a hybrid computational approach consisting of different computational methods to explore the molecular electronic structures, bioactivity and therapeutic potential of piperidine compounds against SARS-CoV-2. The quantum chemical methods are used to study electronic structures of designed derivatives, molecular docking methods are used to see the most potential docking interactions for main protease (MPro) of SARS-CoV-2 while molecular dynamic and MMPBSA analyses are performed in bulk water solvation process to mimic real protein like aqueous environment and effectiveness of docked complexes. We designed and optimized piperidine derivatives from experimentally known precursor using quantum chemical methods. The UV–Visible, IR, molecular orbitals, molecular electrostatic plots, and global chemical reactivity descriptors are carried out which illustrate that the designed compounds are kinetically stable and reactive. The results of MD simulations and binding free energy revealed that all the complex systems possess adequate dynamic stability, and flexibility based on their RMSD, RMSF, radius of gyration, and hydrogen bond analysis. The computed net binding free energy (Δ G b i n d ) as calculated by MMPBSA method for the complexes showed the values of −4.29 kcal.mol−1 for P1, −5.52 kcal.mol−1 for P2, −6.12 kcal.mol−1 for P3, −6.35 kcal.mol−1 for P4, −5.19 kcal.mol−1 for P5, 3.09 kcal.mol−1 for P6, −6.78 kcal.mol−1 for P7, and −6.29 kcal.mol−1 for P8.The ADMET analysis further confirmed that none of among the designed ligands violates the Lipinski rule of five (RO5). The current comprehensive investigation predicts that all our designed compounds are recommended as prospective therapeutic drugs against Mpro of SARS-CoV-2 and it provokes the scientific community to further perform their in-vitro analysis. [ABSTRACT FROM AUTHOR]

Fig. Proposed mechanism of CN/BI 10.0. [Display omitted] • BI was incorporated within CN via molecular engineering (CN/BIx). • Endorsing charge transition dissociation and boosting the photocatalytic performance. • Superior sample CN/BI 10.0 demonstrate remarkable photocatalytic H 2 evolution and photoreduction of CO 2 respectively. • A dual synergetic mechanism of CN/BI 10.0 has been proposed. Due to a growing number of significant vitality and environmental issues, the standardized variation of carbon nitride (CN) for visible-light photocatalytic water splitting is an encouraging scientific topic. By revealing this, the functionalized monomer 2,6-dibromobenzimidazole (BI) was successfully embedded within the heptazine units of CN via a molecular engineering (Co-polymerization process) approach, and the as-synthesized product was named CN/BIx. Thereafter, as-synthesized materials were employed in the photocatalytic production of hydrogen (H 2) via water splitting and CO 2 reduction into CO under visible light irradiance (λ = 420 nm). Surprisingly, the substituent framework of CN, which was intimidated by the description of BI monomer, acted as a substitution reaction material and lubricated the electronic structure of CN by endorsing charge transition dissociation, which in turn boosted its photocatalytic performance under visible irradiation. The CN/BI 10.0 yields 62.8 mol of CO and 18.1 mol of H 2 for 4 h of the catalyzed reaction upon photooxidation under light irradiation, emphasizing the maximum photocatalytic performance with response to CO 2 +. Correspondingly, the H 2 evolution rate (HER) for bulk CN was estimated as 17.6 mol/h1, whereas it was approximated as 203.7 mol/h1 for CN/BI 10.0 , which is 10 times higher than that of CN. Such a phenomenon also predicts a substantial encroachment in the surface area, energy gap, and chemical properties, along with promotes the effective segregation of photoinduced charge separation from the valence band (VB) to the conduction band (CB) of CN, thereby, making it a good alternative for the photocatalytic water and CO 2 reduction reaction process. [ABSTRACT FROM AUTHOR]

[Display omitted] • A triple hybrid computational methodology is used to study modafinil drug derivatives. • Molecular docking was performed with ERα receptor to see potential interactions. • The complexes were further studied molecular dynamics simulations (120 ns). • The MMPBSA binding free energies were also calculated. • Structure-property relationship of compounds were predicted. Breast cancer (Bc a) is the prominent, most commonly detected, and the leading cause of mortality among women. Estrogen receptor alpha (ERα) is considered an important receptor for the proliferation of this disease and its blockage is necessary for the treatment of Bc a. The purpose of the current study is to design novel potential inhibitors against ERα of Bca. We designed modafinil drug derivatives using quantum chemical methods. These newly designed derivatives were put under an in-silico investigation followed by molecular docking simulation, molecular dynamics simulation, and MMPBSA analysis to find novel inhibitors of ERα. Moreover, three reference anticancer drugs; tamoxifen, raloxifene, and toremifene are also studied against ERα of Bc a. The spectroscopic and structural features of sulfoxide-based designed derivatives of modafinil drug M1 ((R)-2-(banzhydrylsulfinyl-N,N diethylacetamide) have been evaluated using different quantum chemical analyses. The findings of the current investigation demonstrate that all studied ligands exhibit the binding energy ranges (-5.3 to −5.8 Kcal/mol). The designed compounds showed effective hydrophobic (alkyl, π -alkyl, π -sigma, π -amide stacked, π - π T-shaped) interactions and hydrogen bond formation and are anticipated to be potential inhibitors against ERα. Additionally, designed derivatives have a good ADMET (absorption, distribution, metabolism, excretion, toxicity) profile and drug-likeness properties obeying RO5 without any toxicity. The stability profile of designed derivatives (M1 - M6) was further validated by molecular dynamics (MD) simulation and calculate binding free energy by the MM-PBSA approach. All ligand–protein complexes showed structural stability over the 120 ns MD simulation time. The MD simulation of the complex system was carried out by RMSD (root-mean-square deviation) of C α atoms of ERα, RMSF (root mean square fluctuations), R g (radius of gyration), SASA (solvent accessible surface area), and dynamic behavior of hydrogen bonds. The MD simulation results illustrate that RMSD for trajectories of designed derivative complexes over 120 ns are within the acceptable deviation range of ∼ 3 Å. The calculations of net binding free energy (Δ G b i n d ) between the designed derivatives and their complexes are found to be −8.50 Kcal/mol (M1) at maximum and −5.197 Kcal/mol (M3) at a minimum among all derivatives. The outcomes of our current in-silico investigation will evoke the scientific community to carry out further in vivo and in vitro studies on designed modafinil derivatives that can be potential therapeutic drug candidates against ERα. [ABSTRACT FROM AUTHOR]

Advanced poly(o-toluidine)@Sn(II)silicate/CNT nanocomposites were synthesized using sol–gel of Sn(II) silicate by varying the mixing volume ratio concentration of inorganic reactant with a fixed mixing volume ratio, i.e., 1:1, of organic polymer. Physico-chemical characterization was conducted using SEM, XRD, FTIR, UV–Vis and TGA. Ion-exchange capacity distribution studies were also conducted to determine the ion-exchange capabilities. The distribution studies revealed high selectivity for Hg 2 + , which is an important environmental pollutant. Due to the selective nature of the composite, an ion selective membrane electrode was designed for determining Hg(II) ions in solutions. The electrode potential remains unchanged within a pH range of 4.0–7.0 and at a working concentration range of 1 × 10 − 1 M to 1 × 10 − 6 M for Hg 2 + ions and a Nerstian slope of 32.14 mV per decade change in Hg 2 + ion concentration. [ABSTRACT FROM AUTHOR]

[Display omitted] • The probe displays a rapid fluorescent response for HSO 3 − ion. • Addition of HSO 3 − exhibits enhancement in blue fluorescence via nucleophilic addition mechanism. • DFT and TD-DFT methods have shed light on the sensing mechanism. • The probe was successfully applied to detect HSO 3 − in food samples. A new pyrene-based chemodosimeter (RS3) has been designed and synthesized, which is found to be a promising fluorescent probe for detection of bisulphite ion in DMSO:Na 2 HPO 4 /citric acid buffer of pH 5. 1H NMR titration indicates that nucleophilic addition of HSO 3 − to vinylic C-atom of RS3 terminates the π-conjugation and consequently enhanced the fluorescence significantly. The sensing mechanism is further confirmed by density functional theory (DFT) and time dependent density functional theory (TD-DFT) methods. The binding constant of the 1:1 RS3 -HSO 3 adduct is found to be 0.7 × 103 M−1. The probe RS3 exhibits high selectivity towards bisulphite ion with a limit of detection of 0.15 µM, which is lower than the maximum permissible limit of bisulfite ion (1.25 µM) in food products required by the European Union Regulations. Further, the probe RS3 has been used for the determination of HSO 3 − in real samples such as distilled water, tap water, red wine, jaggery and white sugar and also successfully applied for the bio-imaging of HSO 3 − in live cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • Symmetrical disubstituted compounds with D-A-D-A-D configuration was synthesized. • Exhibited excellent NLO properties with promising optical limiting threshold values under nanosecond pulse excitation. • A detailed energy level mechanism is proposed for the NLO activity of the molecules. • Formation of charge separation state by photo-induced charge transfer is discussed. Organic materials figure among the most widely investigated nonlinear optical (NLO) materials towards the realization of optical limiters. Among the organic materials, donor–acceptor systems are getting special consideration due to their excellent NLO activities arising from the intramolecular charge transfer (ICT). But NLO activities of many of these systems are restricted by photo-bleaching and limited thermal stability. This deficiency can be overcome by introducing more than one donor–acceptor groups into the framework. Herein we report NLO activities of two symmetrical disubstituted compounds with D-A-D-A-D configuration, containing bis-1,3,4-oxadiazole with phenothiazine backbone in which two different electron donor systems namely naphthalene (NOPON)/4-bromophenyl (BOPOB) were bonded with the phenothiazine-1,3,4-oxadiazole core unit. Solution phase absorption spectrum of these compounds exhibited two peaks, one located in the 300–350 nm regions and a comparatively weak and broad band located at the longer wavelength region attributed to ICT state. Photophysical, electrochemical and excited state life time analysis of the compounds were carried out. HOMO-LUMO energies of the system obtained from DFT calculation are comparable with the experimental values obtained from voltammetric study. NLO and optical limiting behaviour of the compounds were analysed by Z scan technique using a Q switched Nd: YAG laser at 532 nm. Both the compounds exhibited promising limiting threshold values (2.43 J/cm2 for NOPON and 3.80 J/cm2 for BOPOB) comparable with many of the reported values, suggesting their ability to perform as good optical limiters. [ABSTRACT FROM AUTHOR]

Broad band optical limiting action of Cr doped (γ and β)-BBO was demonstrated by Z-scan experiment using first (1064 nm) and second (532 nm) harmonics of Q-switched nanopulsed (9 ns, 10 Hz) Nd:YAG laser. The recorded OA pattern at 532 nm exposes that the dispersed liquids exhibit reverse saturable absorption ascribed due to 2PA process. At 0.05 M Cr doped BBO, peculiar switching of SA (0.63 GW/cm2) to RSA (2.52 GW/cm2) was observed under 532 nm excitation. Increase in 2PA coefficient with on-axis peak intensity and availability of Cr induced near-resonant energy states demonstrate the presence of sequential 2PA (1PA + ESA) process. Interestingly under 1064 nm excitation, Cr doped γ-BBO exhibit 3PA while Cr doped β-BBO possess 2PA process. The addition of Cr has induced transition states in visible and IR region, therefore availability of transition states confirms the involvement of excited ESA process at 1064 nm regime. All the liquids exhibit optical limiting action in which onset optical limiting threshold varies with phase, concentration of Cr and on-axis peak intensity. Comparing the NLA coefficient of Cr doped (γ and β)-BBO in both 532 nm and 1064 nm region, the involvement of trapped state of Cr at 2PA region has improved the absorption coefficient than the real 2PA state of pristine (γ and β)-BBO. Among Cr doped (γ and β)-BBO at 532 nm regime, 0.05 M Cr doped (γ and β)-BBO exhibits low threshold of 0.75 × 1012 W/m2 and 0.57 × 1012 W/m2 respectively. Interestingly at 1064 nm regime, 0.03 M Cr doped (γ and β)-BBO possess better onset limiting threshold of 0.986 × 1012 W/m2 and 2.92 × 1012 W/m2 respectively. Earlier by hydrothermal technique tunability of band structure was achieved by introducing Cr in two different phases of BBO (γ and β) at different concentration (0.01 M, 0.03 M and 0.05 M). Incorporation of Cr without altering the crystal structure of host BBO was confirmed by XRD and Raman analysis. SEM analysis exposes the transformation of nanorod to nanowire (γ-BBO) and irregular platelet to cubic (β-BBO) morphology due to Cr incorporation in BBO. Ground state absorption studies shows Cr doped (γ and β)-BBO possess transition at 532 nm and 1064 nm due to 4A 2g (F) → 4T 1g (F), 4A 2g (F) →4T 2g (F) transition of Cr. Thus by Cr doping in BBO, ESA assisted 2PA and 3PA based broad band optical limiting with higher NLO coefficients was demonstrated successfully. • Cr doped (γ and β)-BBO nanostructures were synthesized by hydrothermal technique. • SEM exposes the transformation of nanorods to nanowire (γ-BBO) and irregular platelet to cubic (β-BBO) morphology. • Under 532 nm excitation, peculiar switching of SA to RSA was observed in 0.05 M Cr doped BBO. • Interestingly under 1064 nm excitation, Cr doped γ-BBO exhibit 3PA while Cr doped β-BBO possess 2PA process. • Cr doped γ-BBO nanostructures exhibit higher NLO coefficient and OLT value than Cr doped β-BBO. [ABSTRACT FROM AUTHOR]