Muhammad Ramzan Saeed Ashraf Janjua

Green Synthesis of Silver Nanoparticles through Reduction with Solanum xanthocarpum L. Berry Extract: Characterization, Antimicrobial and Urease Inhibitory Activities against Helicobacter pylori

A green synthesis route for the production of silver nanoparticles using methanol extract from Solanum xanthocarpum berry (SXE) is reported in the present investigation. Silver nanoparticles (AgNps), having a surface plasmon resonance (SPR) band centered at 406 nm, were synthesized by reacting SXE (as capping as well as reducing agent) with AgNO3 during a 25 min process at 45 °C. The synthesized AgNps were characterized using UV–Visible spectrophotometry, powdered X-ray diffraction, and transmission electron microscopy (TEM). The results showed that the time of reaction, temperature and volume ratio of SXE to AgNO3 could accelerate the reduction rate of Ag+ and affect the AgNps size and shape. The nanoparticles were found to be about 10 nm in size, mono-dispersed in nature, and spherical in shape. In vitro anti-Helicobacter pylori activity of synthesized AgNps was tested against 34 clinical isolates and two reference strains of Helicobacter pylori by the agar dilution method and compared with AgNO3 and four standard drugs, namely amoxicillin (AMX), clarithromycin (CLA), metronidazole (MNZ) and tetracycline (TET), being used in anti-H. pylori therapy. Typical AgNps sample (S1) effectively inhibited the growth of H. pylori, indicating a stronger anti-H. pylori activity than that of AgNO3 or MNZ, being almost equally potent to TET and less potent than AMX and CLA. AgNps under study were found to be equally efficient against the antibiotic-resistant and antibiotic-susceptible strains of H. pylori. Besides, in the H. pylori urease inhibitory assay, S1 also exhibited a significant inhibition. Lineweaver-Burk plots revealed that the mechanism of inhibition was noncompetitive.

Prediction of remarkably large second-order nonlinear optical properties of organoimido-substituted hexamolybdates.

The dipole polarizabilities, dipole moments, density of states, and second-order nonlinear optical (NLO) properties of organoimido derivatives of hexamolybdates have been investigated by using time-dependent density functional response theory. This class of organic-inorganic hybrid compounds possesses remarkably large and eye-catching molecular second-order NLO response, especially [Mo(6)O(17)(NC(16)H(12)NO(2))(FeNC(10)H(9))](2-) (7) and [Mo(6)O(17)(NC(16)H(12)NO(2))(NC(6)H(2)(NH(2))(3))](2-) (6) with static second-order polarizability (beta(vec)) computed to be 15766.27 x 10(-30) esu and 6299.59 x 10(-30) esu, respectively. Thus, these systems have the possibility to be excellent second-order nonlinear optical materials. Analysis of the major contributions to the beta(vec) value suggests that the charge transfer (CT) from polyanion to organic segment (D-A) along the z-axis plays the key role in NLO response; the polyanion acts as a donor (D) whereas organoimido acts as an acceptor (A) in all the studied systems. The computed beta(vec) values increase by incorporation of an electron acceptor (-NO(2)) at the end of the phenyl ring of the organoimido segment. Furthermore, substitution of amino (-NH(2)) or ferrocenyl (-FeC(10)H(9)) at the outer side of polyanion and an electron acceptor (-NO(2)) at the end of the phenyl ring in organoimido segment simultaneously is more important to enhance the optical nonlinearity. Orbital analysis shows that the degree of CT between the polyanion and organoimido segments was increased when ferrocenyl donor was introduced. The present investigation provides important insight into the remarkably large NLO properties of organoimido-substituted hexamolybdates.

Prediction of robustly large molecular second-order nonlinear optical properties of terpyridine-substituted hexamolybdates: structural modelling towards a rational entry to NLO materials.

We have explored an innovative, versatile, and novel molecular hybrid containing polyoxometalate (POM) cluster linked with terpyridine ligand via pi-bridged donor-acceptor (D-A) configuration. The dipole polarizabilities, density of states, and second-order nonlinear optical (NLO) properties of terpyridine-substituted hexamolybdates have been investigated by using time-dependent density functional response theory (TDDFT). This class of organic-inorganic hybrid compounds possesses a robustly large molecular second-order NLO response, especially [Mo(6)O(18)(N(4)C(25)H(16)I(2))](2-) (system 5) and [Mo(6)O(17)(N(4)C(25)H(16)(CN)(2))(N(4)C(25)H(16)(CN)(2))](2-) (system 10) with the static second-order polarizability (beta(vec)) computed to be 1209.25x10(-30)esu and 1622.67x10(-30)esu respectively. Thus, these systems have the possibility to be excellent second-order nonlinear optical materials. Analysis of the major contributions to the beta(vec) value suggests that the charge transfer (CT) from POM-cluster to terpyridine ligand (D-A) along the z-axis plays the key role in the NLO response, POM-cluster (hexamolybdates) acts as a donor (D) whereas terpyridine ligand acts as an acceptor (A) in all the studied systems. The computed beta(vec) values increase by the incorporation of electron acceptors (halogen=F, Cl, Br and I) at the terminus of terpyridine ligand. Furthermore, substitution of trifluoromethoxy (-OCF(3)), trifluoromethyl (-CF(3)), and cyanide (-CN) at the end of terpyridine ligand respectively enhances the optical nonlinearity. Orbital analysis shows that the degree of CT between POM and terpyridine segment was increased in 2D and organometallic/POM hybrid systems. The present investigation provides important and thought provoking insight into the robustly large NLO properties of terpyridine-substituted hexamolybdates.

Tuning Second-Order Non-linear (NLO) Optical Response of Organoimido-Substituted Hexamolybdates through Halogens: Quantum Design of Novel Organic-Inorganic Hybrid NLO Materials

The second-order non-linear optical (NLO) response of organoimido-substituted hexamolybdates has been tuned from 218.61 × 10–30 to 490.10 × 10–30 esu. The dipole polarizabilities and second-order nonlinear optical (NLO) properties of organoimido derivatives of hexamolybdates have been investigated by using the time-dependent density functional response theory (TDDFT). The electron withdrawing ability of F (fluorine) has played an important role in tuning the second-order NLO response in this class of organic-inorganic hybrid compounds; particularly system 6 [Mo6O18(NC16H8F2(CF3)2I)]2– with the static second-order polarizability (βvec ) computed to be 490.10 × 10–30 esu. Thus, our studied systems have the feasibility to be excellent tuneable second-order NLO materials. The analysis of the major contributions to the βvec value suggests that the charge transfer (CT) from POM to organic ligand (D-A) along the z-axis has been enhanced with addition of F atoms at the end phenyl ring which directs head (POM) to tail (fluorinated ring) charge transfer. The computed βvec values have been tuned by incorporation of different halogen atoms at the end phenyl ring of organoimido segment. Furthermore, substitution of two trifluoromethyl (–CF3) groups sideways along with iodine (I) at the terminus of end phenyl ring in the organoimido ligand has a striking influence on tuning the optical non-linearity, as CT from POM to the organoimido ligand was significantly increased. These systematic small changes in molecular composition by substitution of different halogen groups leads to a tuning the NLO response; the so-called ‘ripple effect’ catches this point nicely. Thus, the present investigation provides thought provoking insight into the tuneable NLO properties of organoimido-substituted hexamolybdates.

First Principle Study of Electronic and Non-Linear Optical (NLO) Properties of Triphenylamine Dyes: Interactive Design Computation of New NLO Compounds

In this study, density functional theory and time-dependent density functional theory are used to determine how the size of π-conjugated system influences the absorption spectra and non-linear optical (NLO) properties of dyes. Double and triple bonds, as well the benzene rings, are used in conjugated systems. The results of the theoretical computation show that the absorption spectra are gradually broadened and red-shifted with increases in the conjugation length. Theoretical examination of the NLO properties was performed on the key parameters of polarizability and hyperpolarizability. A notable increase in the non-linear optical response was observed with an increase in the conjugation length of the π-spacer.

Nonlinear optical response of a series of small molecules: quantum modification of π-spacer and acceptor

In this research article, a series of compounds have been designed to investigate the nonlinear optical (NLO) response. The electronic structures, absorption spectra and nonlinear optical response have been calculated by employing quantum chemical methods. The new design of dyes has been proposed by the structural modification of π-spacers/conjugated systems (CS) and terminal acceptors (TA). The quantum modeling and design is based on three phases; in every phase different π-spacer (CS1–CS2) with the acceptors (TA1–TA5) are used around central quinoxaline group. DFT and TDDFT calculations are performed to shed light on how structural modification influences the NLO properties. Polarizability (α), hyperpolarizability (β) and absorption wave length are calculated. These strategies indicate that the thiazole-based conjugated systems (CS2) offer relatively an effective way to improve NLO response. This theoretical framework might be useful to design other organic dyes in the field of electro-optics.Graphical AbstractThe DFT and TDDFT calculations have been performed to shed light on how structural modification influences the NLO properties. Impact of various terminal acceptors (TA) and conjugated systems (CS) has been systematically studied.

Synthesis of Self-Assembled Co3O4 Nanoparticles with Porous Sea Urchin-Like Morphology and their Catalytic and Electrochemical Applications

Novel self-assembled cobalt oxide nanoparticles with sea urchin-like morphology were synthesized using a solvothermal method. It was observed that the product consists of a tube-like arrangement of nanoparticles arising from a base. The base is formed by the arrangement of nanoparticles in the form of dense aggregates. A series of comparative experiments were performed over different time intervals to investigate the mechanism of formation of this morphology. The electrochemical performance of an electrode prepared based on this product was analysed by cyclic voltammetry, chronopotentiometry, and alternating current impedance. The electrochemical study shows that the prepared electrode possesses high capacitance and offers very low resistance against the flow of electrons. The product was used as a catalyst for the reduction of nitrobenzene in aqueous medium. The value of the apparent rate constant of catalysis was found to be as high as previously reported values.

Solvent-Dependent Non-Linear Optical Properties of 5,5′-Disubstituted-2,2′-bipyridine Complexes of Ruthenium(ii): A Quantum Chemical Perspective

In this research article, we reported solvent effects on non-linear optical (NLO) properties of 5,5′-disubstituted-2,2′-bipyridine complexes of ruthenium. The polarizability (α) and hyperpolarizability (β) were calculated in the gas phase. Benzene (ϵ (dielectric constant) = 2.3), THF (ϵ = 7.52), dichloromethane (ϵ = 8.93), acetone (ϵ = 21.01), methanol (ϵ = 33.00), and water (ϵ = 80.10) were used by density functional theory. These solvents cover a wide range of polarities. The results of theoretical investigation showed that the non-linear optical properties were significantly increased with the increase in solvent polarity. The results of this study also showed that similarly to structural modifications, polarity of the medium may play a significant role in modulating the NLO properties.

First Synthetic Study of Cube-Like Cobalt Hydroxystannate Nanoparticles as Photocatalyst for Drimarene Red K-4BL Degradation and Fuel Additive

This research article describes the development of a simple and sensitive approach with less runtime for the estimation of photo degradation of an anthraquinone dye drimarene red K-4BL in the presence of newly synthesized nano catalyst. Hydrothermal approach is used to synthesize cobalt hydroxystannate by using precursor salts of chloride i.e. stannic chloride, cobalt chloride and sodium hydroxide is used as a precipitating agent. Various techniques were used to analyze the product. Two major applications of synthesized nanocubes are investigating the efficiency of modified fuel and as a photocatalyst for dye degradation. Anthraquinone dye (drimarene red K-4BL) is degraded by the newly synthesized nanoparticles which is used as a catalyst in aqueous medium. In the presence of sun irradiation at different concentrations of hydrogen peroxide and catalyst, kinetics of photo catalytic degradation of dye is monitored on ultra violet visible spectrophotometer. Efficiency of modified fuel is analyzed by studying the various parameters such as flash point, fire point, pour point and cloud point, etc. at different dosage of Cobalt hydroxystannate. By changing the dosage of the catalyst, values of these parameters changed significantly.Graphical Abstract

First theoretical framework of di-substituted donor moieties of triphenylamine and carbazole for NLO properties: quantum paradigms of interactive molecular computation

Abstract The dependence of polarisability (α) and hyperpolarisability (β) on donor strength has been systematically studied by employing density functional theory method on triphenylamine (TPA) and carbazole (CZ) based compounds. The electronic structures, absorption spectra and non-linear optical (NLO) response were calculated by using quantum chemical methods. All the calculations were performed in gas phase in presence of solvent. The results reveal that the polarizability (α) and hyperpolarizability (β) significantly increased by the addition of second donor moiety. Similarly, the oscillator strength and light harvesting efficiency were also increased, while absorption wavelength was red-shifted by the addition of second donor moiety. These results indicate that the di-substituted donor is an effective way to improve NLO response. The TPA dyes possess a large second-order non-linear response and this is primarily because of the strong donor-π-acceptor conjugation that is ascribed to the excited state intramolecular charge transfer. These theoretical frameworks of carbon architecture might be advantageous to design other organic charge-transfer compounds. Graphical abstract DFT method has been used to explain the differences in NLO properties of conjugated organic compounds with single and double donor moieties. The compounds/dyes 2 and 4 with double donor moieties have shown significantly enhanced polarizability and hyperpolarizabilty.