Beyond S and Se: Electrocatalytic Hydrogen Production by Tellurolate-Bridged Co(III)-Mn(I) Heterodinuclear Complexes.

In the pursuit of efficient electrocatalysts for the hydrogen evolution reaction (HER), a series of manganese and cobalt heterodinuclear complexes have been synthesized and characterized that have a stark resemblance with the [NiFe]-hydrogenase active site structure. Irradiation of [Mn(CO)] in the presence of 1.5 eq of [NaEPh] [E = S, Se, Te] followed by reaction with [Cp*CoCl] led to the formation of half-sandwiched trichalcogenate-bridged heterodinuclear complexes [{Mn(CO)}(μ-EPh)(CoCp*)] [E = S (); Se () and Te ()].

Extremely large water droplet impact onto a deep liquid pool.

Most studies of droplet impact on liquid pools focus on droplet diameters up to the capillary length (0.27 cm). We break from convention and study extremely large water droplets (1 to 6 cm diameter) falling into a pool of water.

Multidirectional Solvent-Induced Structural Transformation in Designing a Series of Polycatenated Cobalt(II) Coordination Polymers: Impact on Carbon Dioxide and Hydrogen Uptake.

Coordination polymers with external stimuli-responsive structural transformation acquired paramount importance in the advanced material research field due to their eye-catching application to deal with the existing challenging issue, and Co(II) metal complex with d electronic configuration is a renowned candidate for kinetic accountability and has the potentiality of structural transformation. Bearing these factors in mind, here, a Co(II) congener of a previously reported high hydrogen-adsorbing Cu(II)-based coordination polymer (CP), {[Cu(4-bpe)(2-ntp)]} [where 2-ntp = 2-nitroterephthalate and 4-bpe = 1,2-bis-(4-pyridyl)ethane], has been synthesized to study the metal change impact on hydrogen adsorption and solvent-induced structural transformation with their impact on hydrogen uptake. This modified framework has a 2D + 2D → 3D inclined polycatenated framework as comparable to our previously published Cu(II) framework.

Drug-Drug Binary Solids of Nitrofurantoin and Trimethoprim: Crystal Engineering and Pharmaceutical Properties.

With the aim of developing multidrug solids through a tuned crystal engineering approach, we have selected two antiurinary infective drugs, namely, nitrofurantoin (NF) and trimethoprim (TMP) and isolated eight binary drug-drug solid solvates along with a nonsolvated cocrystal. Crystal structure analyses were performed for eight of these solids and rationalized in terms of known supramolecular synthons formed by pyrimidine, imide, and amine functionalities. Notably, the TMP-NF anhydrous cocrystal and its ionic cocrystal hydrate exhibit enhanced equilibrium solubilities compared to pure NF or the simple NF hydrate.

Proton Conductivity and Sorption Study in Three Sulfonic Group Functionalized Mixed Ligand Coordination Polymers and the Impact of Structural Dynamicity on Their Property.

Two new mixed ligand coordination polymers (CPs) that are sulfonic group functionalized, namely, {[Cd(bpe)(5-sip)(HO)]·4HO(bpeH)} () and {[Cd(bte)(5-sip)(HO)]·3HO} () [where 5-sip = trinegative 5-sulfoisophthalate salt, bpe = 4,4'-bispyridylethane, bte = 1,2-bis(1,2,4-triazol-1-yl)ethane] have been synthesized through the variation of the N,N'-donor connectors only, at room temperature by using a slow diffusion technique. The structural analyses of both the complexes by single crystal X-ray diffraction studies clearly revealed the formation of 2D sheets containing guest water molecules entrapped in the 1D channel. A structurally similar reported compound {[Cd(btp)(5-sip)(HO)]·2HO} () has also been synthesized to compare the property of the newly synthesized compound.

Inhibition of the prototropic tautomerism in chrysazine by p-sulfonatocalixarene hosts.

This study explores the interesting effect of p-sulfonatocalix[n]arene hosts (SCXn) on the excited-state tautomeric equilibrium of Chrysazine (CZ), a model antitumour drug molecule. Detailed photophysical investigations reveal that conversion of CZ from its more dipolar, excited normal form (N*) to the less dipolar, tautomeric form (T*) is hindered in SCXn-CZ host-guest complexes, which is quite unexpected considering the nonpolar cavity of the hosts. The atypical effect of SCXn is proposed to arise due to the partial inclusion or external binding of CZ with the hosts, which facilitates H-bonding interactions between CZ and the sulfonate groups present at the portals of the hosts.

Microhydration of 2-Naphthol at Ground, First Excited Triplet, and First Excited Singlet States: A Case Study on Photo Acids.

Molecular interactions of 2-naphthol (nap) with water molecules are studied at the ground, first excited triplet and first excited singlet states, applying DFT and TD-DFT methods. The minimum energy structure of hydrated clusters of 2-naphthol up to four water molecules are selected from several possible input geometries. It is observed that the minimum energy conformer of the tetra-hydrate of 2-naphthol has proton transfer occurring from nap to solvent water molecules, in its first excited singlet state.

Set of Multifunctional Azo Functionalized Semiconducting Cd(II)-MOFs Showing Photoswitching Property and Selective CO Adsorption.

Syntheses, structural characterizations, photoluminescence, and adsorption properties of three new azo-functionalized Cd(II)-MOFs, namely, {[Cd(azbpy)(msuc)]·2.5(HO)} (2), {[Cd(azbpy)(mglu)]·5(HO)} (3), and {[Cd(azbpy)(glu)]·(NO)·MeOH} (4) [where msuc = methylsuccinate; mglut = methylglutarate; glut = glutarate; azbpy = 4,4'-azobispyridine] have been reported. The compounds show different structures only with the variation of aliphatic dicarboxylates.

Sulfonic Group Functionalized Mixed Ligand Coordination Polymers: Synthesis, Characterization, Water Sorption, and Proton Conduction Studies.

Five sulfonic acid group functionalized mixed ligand coordination polymers (CPs), namely, {[Zn(bpeH)(5-sip)(HO)]·(HO)} (1), {[Cu(pyz)(5-Hsip)(HO)]·(HO)} (2), {[Cu(bpee)(5-sip)(HO)]·(HO)(bpeeH)} (3), {[Cu(bpy)(5-Hsip)(HO)]·(HO)} (4), and {[Cu(bpy)(5-Hsip)]·(HO)} (5) [where sip = 5-sulfoisophthalate; bpe = 4,4'-bispyridylethane; pyz = pyrazine; bpee = 4,4'-bispyridylethylene; bpy = 4,4'-bipyridine], have been synthesized with varying different N,N'-donor linkers using slow diffusion techniques at room temperature. The CPs possess guest water filled 1D channels and noncoordinating sulfonic acid or coordinated sulfonate groups, which are interconnected by means of extended intermolecular H-bonding interaction, which supports the humidity dependent proton conductivity of the samples. Under 95% relative humidity (% RH), the CPs exhibit the temperature dependent proton conductivity which is maximum up to in the range of ∼10-10 S cm at 65 °C.

Hydrogen Uptake by an Inclined Polycatenated Dynamic Metal-Organic Framework Based Material.

A 2D + 2D → 3D inclined polycatenated dynamic metal-organic framework of {[Cu(4-bpe)(2-ntp)(HO)]·2HO} [1, where 2-ntp = 2-nitroterephthalate and 4-bpe = 1,2-bis-(4-pyridyl)ethane] has been synthesized and characterized. The variable-temperature powder X-ray diffraction study indicates the dynamic nature of the inclined polycatenated framework, and the dehydrated framework with exposed metal centers exhibits excellent type I H adsorption of 1.94 wt % at 77 K and 1 bar of pressure.

Microhydration of Neutral and Charged Acetic Acid.

A systematic theoretical study has been carried out on the effect of sequential addition of water molecules to neutral and mono positively charged acetic acid molecules by applying first principle based electronic structure theory. Geometry, dipole moment, and polarizability of hydrated clusters of neutral and mono positively charged acetic acid of the type CHCOOH·nHO (n = 1-8) and [CHCOOH·nHO] (n = 1, 2) are calculated at the ωB97X-D/aug-cc-pVDZ level of theory. Free energies of formation of the hydrated acid clusters, at different temperatures and pressures are determined.

Tuned synthesis of two coordination polymers of Cd(II) using substituted bent 3-pyridyl linker and succinate: structures and their applications in anion exchange and sorption properties.

Two new Cd(II) coordination polymers, namely [Cd(3-bpdh)2(ClO4)2]n (1) and {[Cd(3-bpdh)(suc)(H2O)]·3(H2O)}n (2), have been synthesized using a substituted bent N,N'-donor ligand 2,5-bis-(3-pyridyl)-3,4-diaza-2,4-hexadiene (3-bpdh) and aliphatic dicarboxylate disodium succinate (suc) with Cd(II) perchlorate salts at room temperature by a slow diffusion technique for the exploration of our previous reported work. Both the structures were determined by single-crystal X-ray diffraction analysis and also by other physicochemical methods. Structure analysis revealed that complex 1 is a 1D chain structure containing coordinated perchlorate with a metal centre, and complex 2 shows a porous 3D framework with encapsulation of lattice water molecules into the void along the crystallographic a-axis.

Effect of microhydration on dissociation of trifluoroacetic acid.

First-principle-based electronic structure calculations were carried out on microhydrated trifluoroacetic acid clusters (CF3COOH, tfa) to understand its molecular level interaction with water and subsequent ionic dissociation to form CF3COO(-) ion. From several geometrical inputs, the global minimum energy structure of hydrated cluster, tfa · nH2O (n = 1-7), was obtained adopting dispersion-corrected density functional, namely, ωB97X-D, and a set of correlated atomic basis function, aug-cc-pVDZ. It was predicted that tfa requires at least six H2O molecules to dissociate.

Cd(II) based metal-organic framework behaving as a Schottky barrier diode.

A metal-organic framework (MOF) of cadmium(ii) is reported here which is the first example of an experimentally achieved MOF based electronic device, and in the present case it is a Schottky diode.

Conformationally averaged vertical detachment energy of finite size NO3(-)·nH2O clusters: a route connecting few to many.

We report conformationally averaged VDEs (VDE(w)(n)) for different sizes of NO(3)(-)·nH(2)O clusters calculated by using uncorrelated HF, correlated hybrid density functional (B3LYP, BHHLYP) and correlated ab intio (MP2 and CCSD(T)) theory. It is observed that the VDE(w)(n) at the B3LYP/6-311++G(d,p), B3LYP/Aug-cc-Pvtz and CCSD(T)/6-311++G(d,p) levels is very close to the experimentally measured VDE. It is shown that the use of calculated results of the conformationally averaged VDE for small-sized solvated negatively-charged clusters and a microscopic theory-based general expression for the same provides a route to obtain the VDE for a wide range of cluster sizes, including bulk.

Global minimum-energy structure and spectroscopic properties of I2(*-) x n H2O clusters: a Monte Carlo simulated annealing study.

The vibrational (IR and Raman) and photoelectron spectral properties of hydrated iodine-dimer radical-anion clusters, I(2)(*-) x n H(2)O (n=1-10), are presented. Several initial guess structures are considered for each size of cluster to locate the global minimum-energy structure by applying a Monte Carlo simulated annealing procedure including spin-orbit interaction. In the Raman spectrum, hydration reduces the intensity of the I-I stretching band but enhances the intensity of the O-H stretching band of water.

Investigations of the solvent polarity effect on the photophysical properties of coumarin-7 dye.

Photophysical investigations of coumarin-7 (C7) dye in different solvents using absorption, steady-state fluorescence and time-resolved fluorescence measurements reveal the behavioral changes of the dye in nonpolar and other solvents. In moderate to higher polarity solvents, the experimental parameters such as fluorescence quantum yield (Phif), fluorescence lifetime (tauf), radiative rate constant (k(f)), nonradiative rate constant (k(nr)) and Stokes' shift (Deltav) follow almost linear correlations with the Lippert-Mataga solvent polarity parameter Deltaf but show unusual deviations in nonpolar solvents. From the observed results, it is inferred that the dye exists in a planar intramolecular charge transfer structure in moderate to higher polarity solvents, but in nonpolar solvents, the dye exists in a nonplanar structure with its 7-NEt2 group adopting a pyramidal type of configuration.