Design of donor–acceptor–donor (D–A–D) type small molecule donor materials with efficient photovoltaic parameters

Four Donor–Acceptor–Donor (D–A–D) type of donor molecules (M1‐M4) with triphenylamine (TPA) as donor moiety, thiophene as bridge, and thiazolothiazole as acceptor unit were designed and its photovoltaic parameters were equated with reference molecule “R.” DFT functional CAM‐B3LYP/6‐31G (d,p) was found best for geometry optimization and TD‐CAM‐B3LYP/6‐31G (d,p) was found suitable for excited state calculations. Among designed donor molecules, M4 manifests suitable lowest band gap of 4.73 eV, frontier molecular orbital energy levels as well as distinctive broad absorption of 455.3 nm due to the stronger electron withdrawing group. The electron‐withdrawing substituents contribute to red shifts of absorption spectra and better stabilities for designed molecules. The theoretically determined reorganization energies of designed donor molecules suggested excellent charge mobility property. The lower λ_e values in comparison with λ_h illustrated that these four donor materials would be ideal for electron transfer and M4 would be best amongst the investigated molecules with lowest λ_e of 0.0177. Furthermore, the calculated Voc of M4 is 2.04 V with respect to PC₆₀BM (phenyl‐C61‐butyric acid methyl ester). This study revealed that the designed donor materials are suitable and recommended for high performance organic solar cell devices.     

Magnetic,Electrical and Thermal Studies of Polypyrrole-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> Nanocomposites

This research paper comprises of the synthesis of polypyrrole (PPy)-Fe₂O₃ nanocomposites by employing the in situ chemical oxidative polymerization method. The concentration of the filler material was adjusted between 10–50 wt % of PPy. The synthesized nanocomposites were characterized by using X-ray diffraction (XRD). Magnetic analysis and DC electrical conductivity of the samples were carried out using vibrating sample magnetometer (VSM) and two probe DC conductivity method, point towards magnetically active and electrically conductive samples. The magnetic parameters under applied magnetic field demonstrated that the values of coercivity (H _c ), saturation magnetization (M _s ) and remanence (M _r ) can be tailored by carefully controlling the amount of dopant material into the nanocomposites indicating their suitability for controllable switching devices and microwave absorption applications. The DC electrical conductivity showed an increase up to 20 wt % of filler material and thereafter a decrease in the conductivity of nanocomposites with increase in filler content is observed. Thermogravimetric analysis (TGA) showed an increase in thermal stability with an increase in ferrite content in nanocomposites.     

Determination of Br,Rb, Cs,Sc and Na in various plant leaves located in an urban park by neutron activation analysis

In order to determine the effect of airborne emission of trace elements, e.g. Br, Rb Cs, Sc and Na on roadside ecosystem, concentrations were determined in different species of plants from an urban park at Lahore. For monitoring purpose attention was paid to the leaves ofSapindus mukorossis, Alstonia scholaris andDiospyros embryopteris. Different varieties of tissues were found to have different concentration of trace elements when compared among themselves. The concentration of trace element deposition was compared with the values reported in literature. Significant pollution was observed.     

Herbicidal activity of pure compound isolated from rhizosphere inhabiting Aspergillus flavus

In the quest for bioactive natural products of fungal origin, Aspergillus flavus was isolated from rhizosphere of Mentha piperita using Potato Dextrose Agar (PDA) and Czapec Yeast Broth (CYB) nutrient media for metabolites production. In total, three different metabolites were purified using HPLC/LCMS and the structures were established using 500 Varian NMR experiments. Further the isolated metabolites in different concentrations (10, 100, 1000 μg/mL) were tested for herbicidal activity using Completely Randomized design (CRD) against the seeds of Silybum marianum and Avena fatua which are major threats to wheat crop in Pakistan. Among the isolated metabolites, one compound was found active against the test weed species whose activity is reported in the present work. The chemical name of the compound is 2-(1, 4-dihydroxybutan-2-yl)-1, 3-dihydroxy-6, 8-dimethoxyanthracene-9, 10(4aH, 9aH)-dione with mass of 388. Results showed that all seeds germinated in control treatment; however, with the metabolite treated, the growth was retarded to different levels in all parts of the weeds. At a dose of 1000 μg/mL of the pure compound, 100% seeds of S. marianum and 60% seeds of A. fatua were inhibited. Interestingly, the pure compound exhibited less inhibition of 10% towards the seeds of common wheat (Triticum aestivum).     

“Smart” Polymers: Physicochemical Characteristics and Applications in Bio-Separation Strategies

In recent years, smart polymers (SPs), which are also referred to as bio-responsive polymers, have gained considerable attention as a unique class of polymers and their applications have been increasing significantly. These so-called “smart” polymers, either synthetic or biological, have been defined as “polymers designed to respond or undergo physical and structural conformational changes/rearrangement in response to slight changes in their surrounding environment”. They are categorized as thermo-, pH-, electro- and magneto-responsive polymers. The advances in upstream bio-production stages and the high cost associated with downstream chromatographic techniques have pushed the development of new alternatives. In this context, the use of SPs, in combination with non-chromatographic technologies, represents a useful approach to the development of new downstream operation units. With the key scientific advancements, SPs have become the “next generation” of the bio-separation tool for eco-friendlier and cost-effective purification. This review describes the different characteristics and classifications of various “smart” polymers available for use in bio-separation strategy. Focus is also given to the recent advances in SP inclusion in the improvement of alternative non-chromatographic methods in downstream bioprocessings.     

Discriminating three biothiols by using one fluorescent probe

A 1,1′-bi-2-naphthol (BINOL) based dialdehyde (R)-1 is found to exhibit selective fluorescent response towards cellular thiols, _l-Cys, _l-Hcy, and GSH. (R)-1 reacts with _l-Trp to form a Schiff base 2 which quenches the emission of _l-Trp at λ?=?340. Coordination of 2 with Zn(ll) leads to greatly enhanced emission at λ?=?530?nm. When the in situ generated 2 from the combination of the solution of (R)-1 (1.0?×?10^?5?M)?+?Trp (2?equiv) +Zn(OAc)₂ (2 equiv) is treated with _l-Cys, _l-Hcy, and GSH, different fluorescent responses at three emission wavelengths, including 340, 421 and 530?nm, are observed. This allows the in situ generated 2 to be used as a ratiometric fluorescent probe to discriminate these three biothiols. NMR study of (R)-1 with _D- or _l-Cys in the presence of Zn(II) shows that the unique reactivity of Cys provides basis for the selective ratiometric fluorescent response. (R)-1?+?Zn(II) also exhibits enantioselective fluorescent response toward _D- and _l-Cys.     

Eco-friendly synthesis of pyrimidines and its derivatives: A review on broad spectrum bioactive moiety with huge therapeutic profile

Among all heterocyclic compounds, pyrimidine is of prime interest, exhibit broad spectrum of biological activities, because of its occurrence in deoxyribonucleic acid bases. The bioactive moiety pyrimidine has a voluminous therapeutic profile as it is a vital component of a series of natural composites and chemotherapeutic drugs. Since from last 50–60 years, this motif has been used commendably against bacterial, tuberculosis viral, malarial, fungal, and cancerous contagions. Recently, numerous pyrimidine derivatives were synthesized and discussed here, fused with other heterocyclic moieties, pyrazole, coumarine, triazole, alkenyloxindole, hydrazine and others, were also investigated for their bioactivities. Amid all recently reported compounds, several exhibit potentials against breast cancer cell lines. Intensive research has been performed and is going ahead with distinctive emphasis on antineoplastic potential of pyrimidine. These widespread medicinal attributes impulse scientists to synthesize more and more biologically active pyrimidine composites by following simple and eco-friendly routes.     

Octahedral copper(II) carboxylate complex: synthesis,structural description,DNA-binding and anti-bacterial studies

Self-assembly of CuSO₄, para-methyl-2-phenyl acetate and 1,10-phenanthroline afforded good-quality crystalline complex in quantitative yield. The complex was characterized by FTIR and UV-visible spectroscopy, electrochemistry, and powder and single-crystal XRD studies. Its structure was found to possess axially elongated octahedral symmetry with CuO₄N₂ chromophore. Its purity was assessed by powder XRD spectrum. Absorption study yielded a broad band corresponding to ²E_g→²T_2 g transition. Electrochemical solution study indicated diffusion-controlled irreversible electron transfer process corresponding to Cu(II)/Cu(I) redox couple with diffusion coefficient = 7.89(±0.1)×10^?9 cm²s^?1. Results of spectroscopic techniques support each other. Complex exhibited excellent DNA-binding ability through UV-visible spectroscopy and cyclic voltammetry yielding K_b values 1.399 × 10⁴ M^?1 and 5.81 × 10³ M^?1, respectively. The complex exhibited significant activity against bacterial strains Escherichia coli, Micrococcus luteus and Staphylococcus aureus and good activity against Bacillus subtilis. These preliminary studies impart good biological relevance on the synthesized complex.     

生物催化进展:从计算到代谢工程（英文）

经过数次技术研究和超常创新战略的大发展,生物催化逐渐达到工业化水平,从而受到人们特别的关注.基于酶值,通过生物途径生产高附加值化合物和精细工业化学品成为人们最感兴趣的领域之一.更广泛的众多生物化学路线可由酶催化来实现,其中还有一些酶尚未被人们发现.另一方面,由于非同源底物和某些化学过程所必需的苛刻条件,导致酶催化过程的效率低、稳定性差,因而限制了生物催化的应用.因此,开发具有多催化特征、更高效率和稳定性的绿色催化剂,成为生物催化的重中之重.计算科学、代谢工程、合成生物,以及机器学习路线的运用为新催化剂的工程化提供了新方法.本文重点介绍了合成生物学和代谢工程在催化中的作用,讨论了用于催化的机器学习算法和如何选择一种预测蛋白质-配体相互作用的算法;为了预测键合和催化功能,综述了分子对接的重要性;最后给出了结束语、未来挑战和前景展望.     

Structure elucidation,DNA binding,DFT, molecular docking and cytotoxic activity studies on novel single crystal (E)-1-(2-fluorobenzylidene)thiosemicarbazide

Compound 3 {(E)-1-(2-fluorobenzylidene)thiosemicarbazide} – a new Schiff base of thiosemicarbazide has been synthesized, characterized and reported for crystal structure. Planer side chain in the crystal structure was observed co-planer with aromatic ring plane and molecules were connected into centrosymmetric dimmers via intermolecular hydrogen bonding. DFT geometry optimization and the relevant quantum parameters indicated unstable and reactive nature of compound 3. Experimental and theoretical findings for DNA binding by UV–visible, cyclic voltammetry and molecular docking studies showed consistency in kinetic (K_b) and thermodynamic (ΔG) parameters and that compound 3 significantly interacted with DNA via intercalation. Viscometric analysis further comprehended intercalation as possible binding mode of the compound with DNA and non-denaturing of DNA in the presence of 10% aqueous DMSO. Docked parameters further assured the drug like characteristics of the investigated compound as fit in Lipinski’s criteria. Dose dependant cytotoxic activity of compound 3 against human Huh-7 cell line indicated its anti-cancer potential at 100?µg/ml concentration.