Synthesis,Characterization, DNA Binding Studies,Photocleavage, Cytotoxicity and Docking Studies of Ruthenium(II) Light Switch Complexes

A new ligand 3-(1H-imidazo[4,5-f][1,10]phenanthrolin-2yl)phenylboronic acid and its (IPPBA) three ruthenium(II) complexes [Ru(phen)₂(IPPBA)](ClO₄)₂ (1), [Ru(bpy)₂(IPPBA)](ClO₄)₂ (2) and [Ru(dmb)₂(IPPBA)](ClO₄)₂ (3) have been synthesized and characterized by elemental analysis, UV/VIS, IR, ¹H-NMR,¹³C-NMR and mass spectra. The binding behaviors of the three complexes to calf thymus DNA were investigated by absorption spectra, emission spectroscopy, viscosity measurements, thermal denaturation and photoactivated cleavage. The DNA-binding constants for complexes 1, 2 and 3 have been determined to be 7.9?×?10⁵ M^?1, 6.7?×?10⁵ M^?1 and 2.9?×?10⁵ M^?1. The results suggest that these complexes bound to double-stranded DNA in an intercalation mode. Upon irradiation at 365 nm, three ruthenium complexes were found to promote the cleavage of plasmid pBR322 DNA from super coiled form ? to nicked form ??. Further in the presence of Co²⁺, the emission of DNA–Ru(ΙΙ) complexes can be quenched. And when EDTA was added, the emission was recovered. The experimental results show that all three complexes exhibited the “on–off–on” properties of molecular “light switch”. The highest Cytotoxicity potential of the complex1 was observed on the Human alveolar adenocarcinoma (A549) cell line. Good agreement was generally found between the spectroscopic techniques and molecular docked model which provides further evidence of groove binding.     

Study of DNA Light Switch Ru(II) Complexes : Synthesis,Characterization, Photocleavage and Antimicrobial Activity

The three Ru(II) complexes of [Ru(phen)₂dppca]²⁺ (1) [Ru(bpy)₂dppca]²⁺ (2) and [Ru(dmb)₂dppca]²⁺ (3) (where phen = 1,10 phenanthroline, bpy = 2,2-bipyridine, dmb = 2 ,2-dimethyl 2′,2′-bipyridine and polypyridyl ligand containing a single carboxylate functionality dppca ligand (dipyridophenazine-11-carboxylic acid) have been synthesized and characterized. These complexes have been shown to act as promising calf thymus DNA intercalators and a new class of DNA light switches, as evidenced by UV-visible and luminescence titrations with Co²⁺ and EDTA, steady-state emission quenching by [Fe(CN)₆]⁴⁻ and KI, DNA competitive binding with ethidium bromide, viscosity measurements, and DNA melting experiments. The results suggest that 1, 2, and 3 complexes bind to CT-DNA through intercalation and follows the order 1 > 2 > 3. Under irradiation at 365 nm, the three complexes have also been found to promote the photocleavage of plasmid pBR322 DNA.     

Bianchi Type-V Dark Energy Model in a Scalar-Tensor Theory of Gravitation

A spatially homogeneous and anisotropic Bianchi type-V universe with variable equation of state (EoS) parameter and constant deceleration parameter is obtained in a scalar-tensor theory of gravitation proposed by Saez and Ballester (Phys. Lett. A 113:467, 1986). The physical and kinematical properties of the universe have been discussed.     

Cyclisation of 2-(2-aminophenyl)quinazolin-4(3H)-one reexamined: formation of isomeric angular fused quinazolinoquinazolinones and their spectroscopic identification

Cyclisation of 2-(2-aminophenyl)quinazolin-4(3H)-ones on to N₃ and on to N₁ leading to 6-alkyl-(8H)-quinazolino[4,3-b]quinazolin-8-one and 6-alkyl-(13H)-quinazolino[3,4-a]quinazolin-13-one, respectively was described for the first time. The differences in the IR and carbon NMR data of these isomeric fused quinazolinoquinazolinones afford a useful method for distinguishing between the two series.     

EPR and electronic absorption studies of Mn2+ ion in 3CdSO4 · 8H2O single crystals

EPR and electronic absorption spectra of the Mn²⁺ion in 3CdSO₄ · 8H₂O crystals have been studied at 300 K and 80 K. The EPR spectra have     

Asymptotic N-wave Solutions of the Nonplanar Burgers Equation

In this paper, we construct asymptotic N-wave solutions for the nonplanar Burgers equation as   t →∞  via a balancing argument. These constructed asymptotics are compared with the approximate solutions of the nonplanar Burgers equation obtained by an approach due to Parker ( Acoust. Lett. 4 (1981)). We also present a computationally convenient form for the N-wave solution of the nonplanar Burgers equation modifying Sachdev et al.'s ( Stud. Appl. Math . 103 (1999)) approach. The asymptotic N-wave solutions obtained by balancing argument and modification to Sachdev et al.'s approach are validated by a careful numerical study.     

Ordered semigroups containing maximal or minimal elements

Communicted by J. S. Ponizovskii     

Anomalous conversion of 127 keV (E3) transition in134Cs

The total conversion coefficient of the 127.49 keV E3 isomeric transition in the decay of^134mCs was measured using the gamma intensity balance method with the help of a high resolution low energy photon detector. Theα _Tvalue was found to be 5.84±0.47 as against the theoretical value of 6.96, thus showing an anomaly of (16.1±6.7)%. TheK-conversion coefficient,α _kwas also measured using the X-ray peak to gamma ray intensity method and found to be 2.24±0.04 as against the theoretical value of 2.72, which shows an anomaly of (17.6±1.4)% consistent with the experimental anomaly inα _T. TheE3 hindrance factor of the isomeric transition was estimated to be (3.44±0.23) ·10⁴.     

A short convergent synthesis of the [3.2.1]dioxabicyclooctane subunit of sorangicin A via regioselective epoxide opening

In this paper, we disclose the synthesis of the dioxabicyclo[3.2.1]octane subunit of the potent antibiotic sorangicin A. The synthesis was achieved in a convergent manner in 8 steps. Regio- and stereoselective intermolecular epoxide opening, ring-closing metathesis and iodo-etherification are key steps. cis-2-Butene diol has been employed as a common staring material.