Phase behaviour of thermotropic banana-shaped compounds under pressure

The phase behaviour of two achiral bent core banana-shaped compounds, the hexyloxy (compound I) and decyloxy (compound II) members of the 1,3-phenylene bis[N-(2-hydroxy-4-n-alkoxybenzylidene)-4′-aminobenzoate] series was investigated under hydrostatic pressures up to 300?MPa using high pressure differential thermal analysis and light transmission methods. The reversible transition sequence crystal (Cr₁)–B₁ phase–isotropic liquid (I), observed at room pressure for compound I, remains in the pressure region up to c 70?MPa. At higher pressures a pressure-induced crystalline phase (Cr_i) appears between the Cr₁ and B₁ phases, its temperature region becoming wider with increasing pressure. The temperature vs. pressure phase diagram shows a triple point of 72.9?MPa and 160.3°C for the Cr₁, Cr_i and B₁ phases, indicating the lower limit of pressure for the Cr_i phase. In compound II the reversible transition sequence crystal (Cr₁)–B₂ phase–I is seen over the whole pressure region, and the temperature range of the B₂ phase remains unaltered. It is concluded that both the B₁ and B₂ banana phases are stable over the whole pressure region studied.     

Synthesis and characterization of phenol‐based biaryl proton conducting polymers

Biaryl hydroxy polymers with orthogonal disposition of proton transporting ? OH moieties have been synthesized via conventional free radical polymerization. The polymers are characterized for their thermal stability and proton conductivity, and the results are compared with the corresponding styrenic hydroxy polymers. The orthogonal disposition of ? OH moieties in biaryl polymers does result in lower E_a for proton transport. However, the lower E_a values in biaryl polymers did not translate into a net increase in proton conductivity. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Photoinduced hinge-like molecular motion: studies on xanthene-based cyclic azobenzene dimers

[Structure: see text]. Molecular devices incorporating azobenzene units represent active components of smart systems, as they are capable of exhibiting photoregulated cooperative molecular motion. Herein, we describe the synthesis, X-ray crystal analysis, and photochemical and thermal studies of a xanthene based cyclic azobenzene dimer and its precursor. The trans-trans isomer of the azobenzene dimer upon photoirradiation transforms to the cis-cis isomer through an intermediate trans-cis isomer. The X-ray crystal structures of the trans-trans isomer (open) and the cis-cis isomer (closed) provide unambiguous proof for the hinge-like molecular motion in this class of molecules. The inferences drawn from photochemical and thermal studies shed light on the effect of varied substitution and cyclic structures on the different transitions. The lifetime of the cis-cis isomer is estimated to be 6.43 years, whereas the trans-cis isomer is short-lived (2.73 min) at 303 K. A rational explanation for the relative stability of the different isomers is derived from the isokinetic plot and theoretical calculations.     

An Efficient Oxidative Difunctionalisation of 2-Amino-2H-chromene and Antimicrobial Activity of the Synthesized Tetrahydrochromene Derivatives

A novel series of 3-amino-2,2-dialcoxy-7,7-dimethyl-5-oxo-4-phenyl-3,4,5,6,7,8-hexahydro-2H-chromene-3-carbonitriles are synthesized by oxidative difunctionalization (geminal dialkoxylation and migration of the amino group) of 2-amino-4-aryl-7,7-dimethyyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitriles in the presence of iodobenzenediacetate in water medium with excellent yields. All the newly synthesized compounds are characterized by IR, ¹H and ¹³C NMR and Mass spectral data. The representative synthesized analogues are screened in vitro for antibacterial and antifungal activity using Gentamycin sulphate and Nystatin as standard drugs.

     

Microwave-Assisted Synthesis and Antimicrobial Activity of 3-(Arylsulfanyl)-4-hydroxy-2<Emphasis Type="Italic">H</Emphasis>-chromen-2-ones

An efficient microwave-assisted synthesis of 3-(arylsulfanyl)-4-hydroxy-2H-chromen-2-ones by condensation of arenesulfonohydrazides with 4-hydroxy-2H-chromen-2-one in the presence of iodine is described. The synthesized compounds were characterized by spectral data (IR, ¹H and ¹³C NMR, and mass spectra and elemental analyses) and were tested for their in vitro antimicrobial activity against bacterial and fungal organisms.     

Synthesis and Antimicrobial Activity of 3-(1-Aryl-1H-1,2,3-triazol-4-yl)-2-(4-fluorophenyl)-1-(2-hydroxy-4-methoxyphenyl)propan-1-ones

Russian Journal of General Chemistry - A number of novel 3-(1-aryl-1H-1,2,3-triazol-4-yl)-2-(4-fluorophenyl)-1-(2-hydroxy-4-methoxyphenyl) propan-1-ones has been synthesized from...     

State estimation of neural networks with time-varying delays and Markovian jumping parameter based on passivity theory

In this paper, the state estimation problem is investigated for neural networks with time-varying delays and Markovian jumping parameter based on passivity theory. The neural networks have a finite number of modes and the modes may jump from one to another according to a Markov chain. The main purpose is to estimate the neuron states, through available output measurements such that for all admissible time-delays, the dynamics of the estimation error is globally stable in the mean square and passive from the control input to the output error. Based on the new Lyapunov?CKrasovskii functional and passivity theory, delay-dependent conditions are obtained in terms of linear matrix inequalities (LMIs). Finally, a numerical example is provided to demonstrate effectiveness of the proposed method and results.     

Investigation of molecular interactions in binary mixtures of 2-methoxyaniline with cyclic ketones at various temperatures through thermophysical properties

Journal of Thermal Analysis and Calorimetry - Using recently constructed experimental phase diagram isotactic polypropylene–1,2,4,5-tetrachlorobenzene (TeCB), we formulate a physically...