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Novel white light emitting dysprosium oxalate nanocrystals were prepared via microwave assisted co-precipitation method and the photoluminescence characteristics were elucidated on the basis of crystal structure. X-ray powder diffraction and transmission electron microscopy analyses were employed to identify the structure and morphology of the synthesized nanocrystals. Under 364 nm excitation dysprosium oxalate nanocrystals emit blue (480 nm), yellow (572 nm) and red (655 nm) light with chromaticity co-ordinate (0.35, 0.39) which lies in the near white light region. The efficient luminescence exhibited by dysprosium oxalate negating the probable luminescence limiting factors is further investigated by single crystal structure analysis. The crystal structure of dysprosium oxalate facilitates well separated Dy 3+ centres thereby minimizing the energy migration between the luminescent centres, allowing higher concentration of Dy 3+ ions in oxalate matrix without substantial luminescence quenching. The other crystallographic features promoting the luminescence emission of Dy 3+ in oxalate matrix are also discussed in detail in view of the structural features.

The isoreticular expansion and functionalization of charged-polarized porosity has been systematically explored by the rational design of 11 isostructural zwitterionic metal–organic frameworks (ZW-MOFs). This extended series of general structural composition {[M3F(L1)3(L2)1.5]·guests}n was prepared by employing the solvothermal reaction of Co and Ni tetrafluoroborates with a binary ligand system composed of zwitterionic pyridinium derivatives and traditional functionalized ditopic carboxylate auxiliary ligands (HL1·Cl = 1-(4-carboxyphenyl)-4,4′-bipyridinium chloride, Hcpb·Cl; or 1-(4-carboxyphenyl-3-hydroxyphenyl)-4,4′-bipyridinium chloride, Hchpb·Cl; and H2L2 = benzene-1,4-dicarboxylic acid, H2bdc; 2-aminobenzene-1,4-dicarboxylic acid, H2abdc; 2,5-dihydroxy-1,4-benzenedicarboxylic acid, H2dhbdc; biphenyl-4,4′-dicarboxylic acid, H2bpdc; or stilbene-4,4′-dicarboxylic acid, H2sdc). Single-crystal structure analyses revealed cubic crystal symmetry (I-43m, a = 31–36 A) with a 3D pore system of significant voi...

Metformin hydrochloride is an oral hypoglycemic agent prescribed for the treatment of diabetes mellitus type II. Three fluorinated metformin derivatives (MTF1, MTF2 and MTF3) were synthesized and investigated for their human bloodstream – human serum albumin (HSA) interaction studies by multi-spectroscopic techniques (circular dichroism, steady state, time-resolved and synchronous fluorescence), combined with molecular docking and quantum chemical calculation. Steady state and time-resolved fluorescence indicate static fluorescence quenching as the main mechanism. Binding of HSA/metformin is moderate and there is just one main binding site in the protein structure for all samples. In addition, MTF1 can cause weak perturbations on the secondary structure of the albumin, while MTF2 and MTF3 cause moderate perturbations. Synchronous fluorescence spectroscopy showed that MTF1 and MTF3 can decrease the hydrophobicity around the Trp-214 amino acid residue. Molecular docking results suggest hydrogen bonding, van der Waals and hydrophobic interactions as the main binding forces for the association HSA:MTF1 and HSA:MTF2, while for HSA:MTF3 the main binding forces are hydrogen bonding and van der Waals interaction.

Selective monoamine oxidase-B (MAO-B) inhibitors are imperative in the treatment of various neurodegenerative disorders. Herein, we describe the pharmacophore generation and atom-based three-dimensional quantitative structure-activity relationship (3D-QSAR) analyses of previously reported thiophene-based hMAO-B inhibitors by our research group. The aim of this study was to identify the principal structural features that could potentially be responsible for the inhibitory activity of hMAO-B inhibitors. The best pharmacophore model generated was the four-point assay of AHRR.8. The pharmacophore model exhibited good correlation with its predictability of the statistically valid 3D-QSAR analyses. Density functional theory calculations were further employed on the lead molecule (2E)-1-(5-bromothiophen-2-yl)-3-[4-(dimethylamino) phenyl] prop-2-en-1-one (Tb5) to investigate the electrostatic potential surface and analyze the natural bond orbital toward the binding characteristics. Molecular dynamics simulations were performed to characterize the molecular level interactions and relative energies of the hMAO isoforms: hMAO-A and hMAO-B with three potent and selective hMAO-B inhibitors (Tb5, Tb6, and Tb9). The results of both continuous and accelerated molecular dynamics simulations demonstrate a distinct preference of the three ligands to bind to hMAO-B rather than hMAO-A.

In the type II diabetes mellitus, Metformin hydrochloride is recommended as a common FAD approved drug. Synthesis of novel metformin series has been widely explored, mainly due to its biological importance and to improve their pharmacokinetic profile. Generally, human serum albumin (HSA) is the main protein used to study drug viability in vitro analysis. Thus, the present study reports the synthesis of three new halogenated metformin derivatives (MFCl, MFBr and MFCF3) and its interaction toward HSA by multiple spectroscopic techniques (UV-Vis, circular dichroism, steady-state, time-resolved and synchronous fluorescence), combined to computational methods (molecular docking and quantum chemical calculation). The interaction between each halogenated metformin derivative and HSA is spontaneous (ΔG°ΔS°>0), moderate (Ka and Kb ≈ 104 M−1) and occurs preferentially in the subdomain IIA (close to Trp-214 residue). Molecular docking results suggested hydrogen bonding, van der Waals and hydrophobic interactions as the main binding forces. Quantum chemical calculations suggested imino groups as the most intense electrostatic negative potentials, while the positive electrostatic potential is located at the hydrogen atoms on N,N-dimethyl and the phenyl systems which can help the hydrophobic interactions. Communicated by Ramaswamy H. Sarma

The structural features leading to the intense quenching free luminescence exhibited by europium oxalate nanocrystals, poly[[hexaaquatri-μ2-oxalato-dieuropium] 4.34-hydrate], {[Eu2(C2O4)3(H2O)6]·4.34H2O} n , is the focal point of this report. Europium oxalate nanocrystals were synthesized by a simple microwave-assisted co-precipitation method. Powder X-ray diffraction analysis revealed the monoclinic structure of the nanocrystals and the phase purity. The morphology and particle size were examined by transmission electron microscopy (TEM) analysis. Luminescence measurements on a series of samples of La2–x Eu x (C2O4)3·10H2O, with x varying in the range 0.1 to 2, established the quenching free nature exhibited by the europium oxalate nanocrystals. A single-crystal structure analysis was carried out and the quenching free luminescence is explained on the basis of the crystal structure. A detailed photoluminescence characterization was carried out using excitation and emission studies, decay analysis, and CIE coordinate and colour purity evaluation. The various spectroscopic parameters were evaluated by Judd–Ofelt theoretical analysis and the results are discussed on the basis of the crystal structure analysis.

A series of 13 phenyl substituted thiosemicarbazones (SB1–SB13) were synthesized and evaluated for their inhibitory potential towards human recombinant monoamine oxidase A and B (MAO-A and MAO-B, respectively) and acetylcholinesterase. The solid state structure of SB4 was ascertained by the single X-ray diffraction technique. Compounds SB5 and SB11 were potent for MAO-A (IC(50) 1.82 ± 0.14) and MAO-B (IC(50) 0.27 ± 0.015 μM), respectively. Furthermore, SB11 showed a high selectivity index (SI > 37.0) for MAO-B. The effects of fluorine orientation revealed that SB11 (m-fluorine) showed 28.2 times higher inhibitory activity than SB12 (o-fluorine) against MAO-B. Furthermore, inhibitions by SB5 and SB11 against MAO-A and MAO-B, respectively, were recovered to near reference levels in reversibility experiments. Both SB5 and SB11 showed competitive inhibition modes, with K(i) values of 0.97 ± 0.042 and 0.12 ± 0.006 μM, respectively. These results indicate that SB5 and SB11 are selective, reversible and competitive inhibitors of MAO-A and MAO-B, respectively. Compounds SB5, SB7 and SB11 showed moderate inhibition against acetylcholinesterase with IC(50) values of 35.35 ± 0.47, 15.61 ± 0.057 and 26.61 ± 0.338 μM, respectively. Blood–brain barrier (BBB) permeation was studied using the parallel artificial membrane permeation assay (PAMPA) method. Molecular docking studies were carried out using AutoDock 4.2.

The supramolecular structural features of organic molecules are very important with regard to their widespread properties in both solids and solutions. Herein, we describe the synthesis of a novel multifunctional 2-pyridone derivative, namely 6-(4-chlorophenyl)-5-formyl-4-methylsulfanyl-2-oxo-1,2-dihydropyridine-3-carbonitrile, C14H9ClN2O2S, denoted P1, and its structural features were established through X-ray crystallography. A Hirshfeld surface analysis followed by a two-dimensional fingerprint plot analysis was carried out. A frontier molecular orbital investigation and natural bond orbital (NBO) calculations explored the charge-transfer interactions associated with the molecular system. The optical properties of the 2-pyridone derivative were elucidated through UV–Vis absorption and emission spectroscopy, indicating a strong blue emissive nature with a colour purity of 82.5%, a short-lived lifetime and a large Stokes shift. Time-dependent density functional theory (TD-DFT) was used to gain some insight into the absorption behaviour and emissive characteristics of P1.