Showing papers by "Bachcha Singh published in 2015"

Tuning the thermotropic properties of liquid crystalline p-substituted aroylhydrazones

Abstract: The synthesis and mesomorphic properties of forty substituted aroylhydrazones with peripheral mono-, di- and tri- alkoxy chains derived from a p-amino aroylhydrazone core are described. The compounds with two side chains exhibited a smectic A phase, while the compounds with six soft alkoxy side chains at symmetrical positions formed a rectangular columnar mesophase. The structures of these mesophases were confirmed by differential scanning calorimetry (DSC) analysis, polarized optical microscopy (POM) and powder X-ray diffraction (XRD) studies. Raman studies with the help of density functional theory on some of the mesogenic members have been performed to understand the changes in the intermolecular interactions during phase transitions. A structure–property relationship has been deduced, and mesogenic properties are found to be dependent on the chain length, density and position of the alkoxy chains around the molecular core.

Microwave-assisted synthesis and mesomorphic investigations of p-substituted aroylhydrazones and their nickel(II) and copper(II) complexes

Abstract: The present study is focused on the development of green microwave process for the synthesis of mesogenic substituted aroylhydrazones and their nickel(II) and copper(II) complexes. The compounds have been synthesised by microwave-assisted as well as thermal methods for comparison purpose. The compounds were structurally characterised by using suitable spectroscopic techniques. The mesomorphic properties were studied by differential scanning calorimetric analysis and polarising optical microscopy. The stable molecular structures of the mesogenic methylidenehydrazinato-nickel(II) complex have been obtained by density functional theoretical method to understand the structural origin responsible for the mesomorphic property.

Microwave-assisted synthesis, characterisation and mesomorphic investigations of novel disubstituted aroylhydrazones

Abstract: The present study is focused on the development of green microwave process for the synthesis of mesogenic substituted aroylhydrazones and their structure–mesophase relationship study. Two new liquid crystalline series of disubstituted aroylhydrazones with (ABB(OH)H-n) and without lateral hydroxyl group (ABBH-n) (n = 6–16) have been synthesised by microwave-assisted methods. The compounds were structurally characterised by using suitable spectroscopic techniques. The mesomorphic properties of the series of aroylhydrazones were examined using differential scanning calorimetric analysis and polarising optical microscopy. The relationship between structure and mesogenic properties was analysed by comparison of the present series and earlier reports on homostructural series of aroylhydrazones. Thus, the effects of substitution of phenyl rings with ester and ether linking group at both terminals and introduction of hydroxyl group at lateral position on stability of mesophase and their width were investigated. I...

99m Tc labeled macrocyclic aza-oxa and aza-thia probes: synthesis, characterization and in vitro & in vivo biological studies

Abstract: Macrocyclic chelating agents 1-oxa-4,7,10-triazacyclopentadecane-3,11-dione (OTDD) and 1-thia-4,7, 10-triazacyclododecane-3,11-dione (TTDD) have been synthesized and labeled with radionuclide (99mTc), with radiolabeling efficiency 97.6 and 98.4 % respectively. The radiochemical purity of labeled complex (99mTc-OTDD and 99mTc-TTDD) was determined 97.5 and 98.1 %, respectively. The in vitro stability of the labeled chelates in human serum exhibited only <8 % dissociation upto 24 h. The in vivo distribution pattern of the labeled chelators in BALB/c mice suggested that major route of excretion in 99mTc-TTDD is hepatobilliary and minor is renal, while in case of 99mTc-OTDD hepatobilliary as well as renal both comparable. The in vivo blood kinetic studies of radio-complexes of 99mTc-OTDD and 99mTc-TTDD showed 99.26 and 99.4 % blood clearance over 24 h post injection. The biological half-life of 99mTc-OTDD and 99mTc-TTDD with t1/2(F) 1 h 10 min, t1/2(S) 18 h 50 min and t1/2(F) 1 h 42 min, t1/2(S) 18 h 20 min respectively. In vitro cytotoxicity study of OTDD and TTDD did not exhibit any significant antiproliferative property against cancer cells of human glioblastoma U-87, U373 and cervical SW756, HeLa cell lines.