Synergistic reductive catalytic effects of an organic and inorganic hybrid covalent organic framework for hydrogen fuel production.

Electrocatalytic hydrogen generation in alkaline medium has become widely used in a variety of sectors. However, the possibility for additional performance improvement is hampered by slow kinetics. Because of this restriction, careful control over processes such as water dissociation, hydroxyl desorption and hydrogen recombination is required. Covalent organic frameworks (COFs) based on porphyrin and polyoxometalates (POMs) show encouraging electrocatalytic performance, offering a viable route for effective and sustainable hydrogen generation. Their specific architectures lead to increased electrocatalytic activity, which makes them excellent choices for developing water electrolysis as a clean energy conversion method in the alkaline medium. In this regard, TTris@ZnPor and Lindqvist POM were coordinated to create a new eco-friendly and highly active covalent organic framework (TP@VL-COF). In order to describe TP@VL-COF, extensive structural and morphological investigations were carried out through FTIR, 1H NMR, elemental analysis, SEM, fluorescence, UV-visible, PXRD, CV, N2-adsorption isotherm, TGA and DSC analyses. In an alkaline medium, the electrocatalytic capability of 20%C/Pt, TTris@ZnPor, Lindqvist POM and TP@VL-COF was explored and compared for the hydrogen evolution reaction (HER). The TP@VL-COF showed the best catalytic efficiency for HER in an alkaline electrolyte, requiring just a 75 mV overpotential to drive 10 mA cm-2 and outperforming 20%C/Pt, TTris@ZnPor, Lindqvist POM and other reported catalysts. The Tafel slope value also indicates faster kinetics for TP@VL-COF (114 mV dec-1) than for 20%C/Pt (182 mV dec-1) TTris@ZnPor (116 mV dec-1) and Lindqvist POM (125 mV dec-1).

Synthesis and Antioxidant Studies of 2,4-Dioxothiazolidine-5-acetic Acid Based Organic Salts: SC-XRD and DFT Approach.

In the current study, two organic salts (1 and 2) are synthesized, and then crystalline structures are characterized by FTIR, UV spectroscopy, and X-ray crystallographic studies. The organic salts 1 and 2 are optimized at the M06/6-311G(d,p)level of theory and further utilized for analysis of natural bond orbitals (NBOs), natural population, frontier molecular orbitals (FMOs), and global reactivity parameters, which confirmed the stability of the studied compounds and charge transfer phenomenon in the studied compounds. The studies further revealed that 1 and 2 are more stable than 3. The lowest energy merged monomer-coformer conformations were docked as flexible ligands with rigid fungal proteins and DNA receptors. The stagnant binding of the monomer through two H bonds with protein was observed for ligands 1 and 3 while different pattern was found with 2. The coformers formed a single H bond with the active site in 2 and 3 and a single pi-arene H interaction in 1. The two-point ligand-receptor interactions hooked the monomer between DNA base pairs for partial intercalation; pi stacking with additive hydrogen bonding with the base pair led to a strong benzimidazole interaction in 1 and 2, whereas ethylene diamine formed weak H bonding. Thus, the molecular docking predicted that the coformer exhibited DNA intercalation reinforced by its salt formation with benzimidazole 1 and methyl benzimidazole 2. Antioxidant studies depicted that 3 has a higher IC50 value than that of 2,4-D and also the largest value among the studied compounds, whereas 2 showed the lowest value among the studied compounds.

The development of chiral metal-organic frameworks for enantioseparation of racemates.

MIL-101(Cr), an achiral metal-organic framework, made up of a terephthalic acid ligand and a metal chromium ion was selected as a template. Its structural features are unsaturated Lewis acid sites that can be easily activated and it has an extremely high specific surface area, big pore size, and good thermal/chemical/water stability. This achiral framework was modified to introduce chirality within the structure to develop chiral metal-organic frameworks (CMOFs). Here, natural chiral ligands, amino acids (l-proline, l-thioproline and l-tyrosine), were selected for post synthetic modification (PSM) of MIL-101(Cr). This is a very simple, clean and facile methodology with respect to the reactants and reaction conditions. CMOFs 1-3 abbreviated as MIL-101-l-proline (CMOF-1), MIL-101-l-thioproline (CMOF-2) and MIL-101-l-tyrosine (CMOF-3) were prepared by introducing l-proline, l-thioproline and l-tyrosine as chiral moieties within the framework of (Cr). These CMOFs were characterized by FTIR, PXRD, SEM, and thermo gravimetric analysis. Chirality within these CMOFs 1-3 was established by circular dichroism (CD) and polarimetric methods. These three CMOFs 1-3 showed enantioselectivity towards RS-ibuprofen, RS-mandelic acid and RS-1-phenylethanol to varying extents. Their enantioselectivity towards racemates was studied by chiral HPLC and polarimetry.

Targeted drug delivery systems: synthesis and in vitro bioactivity and apoptosis studies of gemcitabine-carbon dot conjugates.

Gemcitabine (GEM) is used to treat various cancers such as breast, pancreatic, non-small lung, ovarian, bladder, and cervical cancers. GEM, however, has the problem of non-selectivity. Water-soluble, fluorescent, and mono-dispersed carbon dots (CDs) were fabricated by ultrasonication of sucrose. The CDs were further conjugated with GEM through amide linkage. The physical and morphological properties of these carbon dot-gemcitabine (CD-GEM) conjugates were determined using different analytical techniques. In vitro cytotoxicity and apoptosis studies of CD-GEM conjugates were evaluated by various bioactivity assays on human cell lines, MCF-7 (human breast adenocarcinoma), and HeLa (cervical cancer) cell lines. The results of kinetic studies have shown a maximum drug loading efficacy of 17.0 mg of GEM per 50.0 mg of CDs. The CDs were found biocompatible, and the CD-GEM conjugates exhibited excellent bioactivity and exerted potent cytotoxicity against tumor cells with an IC50 value of 19.50 µg ml-1 in HeLa cells, which is lower than the IC50 value of pure GEM (∼20.10 µg ml-1). In vitro studies on CD-GEM conjugates demonstrated the potential to replace the conventional administration of GEM. CD-GEM conjugates are more stable, have a higher aqueous solubility, and are more cytotoxic as compared to GEM alone. The CD-GEM conjugates show reduced side effects in the normal cells along with excellent cellular uptake. Hence, CD-GEM conjugates are more selective toward cancerous cell lines as compared to non-cancerous cells. Also, the CD-GEM conjugates successfully induced early and late apoptosis in cancer cell lines and might be effective and safe to use for in vivo applications.

Pt-Ni@PC900 Hybrid Derived from Layered-Structure Cd-MOF for Fuel Cell ORR Activity.

Fuel cell technology is the supreme alternate option for the replacement of fossil fuel in the current era. Pt alloys can perform well as fuel cell electrodes for being used as catalytic materials to perform the very notorious oxygen reduction reaction. In this regard, first, a layered metal-organic framework with empirical formula [C8H10CdO7] n ·4H2O is synthesized and characterized using various experimental and theoretical techniques. Then, a nanostructured porous carbon material with a sheet morphology (PC900) having a high BET surface area of 877 m2 g-1 is fabricated by an inert-atmosphere thermal treatment of the framework upon heating up to 900 °C. Pt and Ni nanoparticles are embedded into PC900 to prepare a homogenized hybrid functional material, i.e., Pt-Ni@PC900. The Pt-Ni@PC900 hybrid is proved to be an excellent ORR catalyst in terms of half-wave potential and limiting current density with 7% Pt loading compared with the commercially available 20% Pt/C catalyst. Pt-Ni@PC900 also shows stability of current up to 12 h with only a very small variation in current. This work highlights the importance of Pt alloys in future large-scale commercial applications of fuel cells.

catena-Poly[[tri-phenyl-tin(IV)]-µ-N-(4-acetyl-phen-yl)maleamato].

The crystal structure of the polymeric title compound, [Sn(C6H5)3(C12H10NO4)] n , comprises polymeric chains whereby adjacent Sn atoms are bridged by carboxyl-ate and amide carbonyl O atoms [Sn-O = 2.115 (15) and 2.653 (1) Å, respectively]. The Sn(IV) atom is five-coordinated showing a distorted trigonal-bipyramid geometry, with the three phenyl ipso-C atoms defining the trigonal plane and the axial positions occupied by O atoms [O-Sn-O = 171.91 (5)°]. Intra-molecular N-H⋯O hydrogen bonding leads to a seven-membered loop. There is an intra-molecular C-H⋯O inter-action within the polymeric chain. An inter-molecular C-H⋯O inter-action along c links the polymeric chains into sheets which are linked into a three-dimensional network via C-H⋯π inter-actions.

Electrochemical and spectroscopic investigations of carboxylic acid ligand and its triorganotin complexes for their binding with ds.DNA: in vitro biological studies.

A carboxylic acid ligand, (Z)-4-(4-acetylphenylamino)-4-oxobut-2-enoic acid (APA-1), and its triphenyl-(APA-2) and tributyl-tin(IV) (APA-3) compounds have been synthesized and investigated for their binding with ds.DNA using UV-visible spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and viscosity measurements under physiological conditions of pH and temperature. The experimental results from all techniques i.e. binding constant (Kb), binding site size (n) and free energy change (ΔG) were in good agreement and inferred spontaneous compound-DNA complexes formation via intercalation. Among all the compounds APA-3 showed comparatively greater binding at pH 4.7 as evident from its greater Kb values {APA-3: Kb: 5.63×10(4)M(-1) (UV); 7.94×10(4)M(-1) (fluorescence); 9.91×10(4)M(-1) (CV)}. Electrochemical processes of compounds before and after the addition of DNA were found diffusion controlled. Among all compounds, APA-3 exhibited best antitumor activity.

Synthesis, crystal structure, DNA binding and in vitro biological studies of Ni(II), Cu(II) and Zn(II) complexes of N-phthaloylglycine.

Ni(II), Cu(II) and Zn(II) metal complexes of N-phthaloylglycine were synthesized, characterized, reported for single crystal X-ray diffraction analysis for Ni(II) complex, and investigated for their binding with DNA under physiological conditions, using spectroscopic (UV-visible and fluorescence) and hydrodynamic techniques. Experimental results from both spectroscopic methods were comparable and further supported by viscosity measurements. Binding constant "K(b)" obtained from both spectroscopic methods revealed significant binding of compounds with DNA via intercalation. Among all compounds comparatively good DNA binding was found for Zn(II) complex. Free energies of compounds-DNA interactions indicated spontaneity of their binding. Dynamic and bimolecular enhancement values disclose static process involved in compounds-DNA complex formation. All compounds exhibited broad range antibacterial, while Zn(II) complex exhibited best antitumor activity.

Caffeine-N-phthaloyl-ß-alanine (1/1).

The title co-crystal [systematic name: 3-(1,3-dioxoisoindolin-2-yl)propanoic acid-1,3,7-trimethyl-1H-purine-2,6(3H,7H)-dione (1/1)], C(8)H(10)N(4)O(2)·C(11)H(9)NO(4), is the combination of 1:1 adduct of N-phthaloyl-ß-alanine with caffeine. The phthalimide and purine rings in the N-phthaloyl-ß-alanine and caffeine mol-ecules are essentially planar, with r.m.s. deviations of the fitted atoms of 0.0078 and 0.0118 Å, respectively. In the crystal, the two mol-ecules are linked via an O-H⋯N hydrogen bond involving the intact carb-oxy-lic acid (COOH) group. The crystal structure is consolidated by C-H⋯O inter-actions. The H atoms of a methyl group of the caffeine mol-ecule are disordered over two sets of sites of equal occupancy.

The 1:1 adduct of caffeine and 2-(1,3-dioxoisoindolin-2-yl)acetic acid.

IN THE CRYSTAL STRUCTURE OF THE TITLE ADDUCT [SYSTEMATIC NAME: 2-(1,3-dioxoisoindolin-2-yl)acetic acid-1,3,7-trimethyl-1,2,3,6-tetra-hydro-7H-purine-2,6-dione (1/1)], C(8)H(10)N(4)O(2)·C(10)H(7)NO(4), the components are linked by an O-H⋯N hydrogen-bond and no proton transfer occurs.

catena-Poly[[diaqua-calcium]bis-[µ-2-(1,3-dioxoisoindolin-2-yl)acetato]-κO,O':O;κO:O,O'].

In the title complex, [Ca(C(10)H(6)NO(4))(2)(H(2)O)(2)](n), the Ca(II) atom lies on a twofold rotation axis and adopts a dodeca-hedral geometry. The Ca(II) atom is octa-coordinated by two O atoms from two water mol-ecules and six O atoms from four acetate ligands. Each acetate acts as a tridentate ligand bridging two Ca(II) atoms, resulting in a chain running along the c axis. O-H⋯O and C-H⋯O hydrogen bonds connect the chains into a two-dimensional network parallel to [011]. π-π inter-actions between adjacent isoindoline-1,3-dione rings [centroid-centroid distance = 3.4096 (11) Å] further consolidate the structure. One of the carboxylate O atoms is disordered over two sites in a 0.879 (12):0.121 (12) ratio.

Ethyl 2-[3-(3,5-Dinitrobenzo-yl)thio-ureido]benzoate.

In the title compound, C(17)H(14)N(4)O(7)S, the dihedral angle between the two benzene rings is 9.04 (15)°. The centroid-centroid distance of 3.9825 (19) Šbetween nearly parallel benzene rings of adjacent mol-ecules suggests the existence of π-π stacking. Inter-molecular and intra-mol-ecular N-H⋯O hydrogen bonding is present in the structure. The eth-oxy group is disordered over two sets of sites with an occupancy ratio of 0.580 (15):0.420 (15). The crystal studied was an inversion twin.

catena-Poly[[triphenyl-tin(IV)]-µ(2)-[3-(cyclo-hexyl-carbamo-yl)propanoato-κO:O]].

The Sn atom in the polymeric title compound, [Sn(C(6)H(5))(3)(C(10)H(16)NO(3))](n), is five-coordinated within a trans-C(3)O(2) donor set that defines an approximate trigonal-bipyramidal geometry. The carboxyl-ate ligand is monodentate and the amide O atom bridges a symmetry-related Sn atom, generating a chain along [010] with a linear topology. An intra-molecular carboxyl-ate-carbonyl N-H⋯O hydrogen bond is responsible for the curved conformation within the carboxyl-ate ligand.

catena-Poly[[triphenyl-tin(IV)]-µ-2-(cyclo-hexyl-amino-carbon-yl)benzoato-κO:O].

In the title polymeric complex, [Sn(C(6)H(5))(3)(C(14)H(16)NO(3))](n), adjacent triphenyl-tin cations are bridged by the N-cyclo-hexyl-phthalamate anion through the carboxyl-ate and carbonyl O atoms, forming a helical chain running along the b axis. The amide N atom is a hydrogen-bond donor to the uncoordinated carboxyl-ate O atom. The geometry at the five-coordinate Sn atom is trans-C(3)SnO(2) trigonal-bipyramidal.

2-[2-(1,3-Dioxoisoindolin-2-yl)acetamido]-acetic acid.

The title mol-ecule, C(12)H(10)N(2)O(5), is non-planar with dihedral angles of 89.08 (7) and 83.21 (7)° between the phthalimide and acetamide mean planes, and the acetamide and acetic acid mean planes, respectively. In the crystal, symmetry-related mol-ecules are linked via N-H⋯O and O-H⋯O hydrogen bonds, forming an undulating two-dimensional network. There are also a number of weak C-H⋯O inter-actions, leading to the formation of a three-dimensional arrangement.