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101.
Milind S. Thakare Nilesh S. Pawar Vishnu A. Adole Dipak B. Patil Vikas Patil 《印度化学会志》2022,99(10):100670
A novel strategy, involving anchoring and un-anchoring of coumarin based fluorophore, has been established for the selective detection of Au3+ species. Selective sensing of Gold (Au3+) was triggered due to alkynophilicity of gold ions to create lateral fluorescence of a latent fluorophore. The 4-methyl-2-oxo-2H-chromen-7-yl 2-(2-phenylethynyl) benzoate (CEB) probe was synthesized by reacting 7-hydroxy-4-methylcoumarin with iodo-benzoic acid. CEB probe has an absorption at 300 nm and 335 nm which decreases gradually and new absorption appeared at 406 nm due to Au3+ promoted ester hydrolysis selectively over other metal ions with great sensitivity, which accompanies a turn on fluorescence change produced by 7-hydroxy coumarin. The principle behind this sensing strategy is activation of triple bond induced uniquely by Au+3 ions leading to cascade and delivers active fluorophore. The sensing mechanism was proposed and supported by 1H NMR, MS and TD-DFT experiments. The density functional theory (DFT) and time dependent density functional theory (TD-DFT) theoretical results of the CEB-probe and Au3+ reaction is in good agreement with the experimental results. Additionally, probe could be well incorporated onto the test strips for effective detection of Au3+. 相似文献
102.
JPC – Journal of Planar Chromatography – Modern TLC - A precise, robust and accurate high-performance thin-layer chromatography (HPTLC) method has been developed for the simultaneous... 相似文献
103.
Rituparna Karmaker Naruti Longkumer Kikoleho Richa Dipak Sinha Upasana Bora Sinha 《印度化学会志》2022,99(8):100574
Quaternary ammonium tribromides (QATBs) have garnered interest for nearly a century now. Various types of tribromides have been synthesized over the years and their diverse applications have been extensively reported. However, despite the fact that these reagents are touted as safer alternatives to the very poisonous bromine, there is insufficient information on the structure of Br3? in QATB systems and there is still no clear explanation for how the tribromide ion (Br3?) participates in bromination reactions. This paper reports a through structural assessment of Br3?, followed by an attempt was made to fully understand the mechanistic behaviour of tribromide during bromination of aromatic compounds. 相似文献
104.
Herein, pleasing the advantageous of both Brønsted and Lewis acidic site of Si-BLAIL the condensation-aromatization reaction has been carried out. The striking distinctiveness of work is optimum reaction condition, easy work-up, high yield, catalyst recyclability, non-inertness of reaction flask, simple catalyst loading method. The decreases in the amount of catalyst and reaction time shows good to high (71%–93%) yield suggests about the involvement of some interesting mechanism such as cooperative catalysis. The mechanism has been hypothesizes as, the Si-BLAIL increase the efficiency of condensation reaction possibly by providing the proton in 2-position of cationic imidazolium ring of BLAIL through the hydrogen bond interaction with carbonyl group and nucleophilic activation during aromatization by hydrogen bond acceptor ability of Lewis adduct anion of BLAIL. The catalyst Si-BLAIL shows massive affirm for industrial applications. The Si-BLAIL has identified as the best acid catalyst for 2-(4-nitrophenyl) benzimidazole synthesis with additional benefits of cooperative catalysis. 相似文献
105.
Rupam Sen Dipak K. Hazra Subratanath Koner Madeleine Helliwell Monika Mukherjee Ashis Bhattacharjee 《Polyhedron》2010
A series of dimeric lanthanide carboxylato complexes [La(5-Br-NIC)3(H2O)2]2·H2O (1); [Gd(5-Br-NIC)3(H2O)2]2 (2), [5-Br-NIC = 5-bromonicotinate] and [Sm(NIC)3(H2O)2]2 (3) [NIC = nicotinate], have been hydrothermally synthesized and structurally characterized by single crystal X-ray analysis. Complexes 1, 2 and 3 are of similar structure and consist of a basic unit [La(carboxylato)3(H2O)2]2. In compound 1 lanthanide cation is surrounded by one chelating 5-bromo-nicotinato ligand, two bridging oxygen atoms from 5-bromo-nicotinato and two water molecules, in which each La(III) ion is nine coordinated in a tricapped prismatic geometry. However, in compounds 2 and 3 four carboxylate groups link a pair of lanthanide atoms in the O,O′-bridging mode to generate a paddle-wheel-like centrosymmetric dimer. All the compounds exhibit excellent catalytic performance in olefin epoxidation reaction. The variable temperature magnetic susceptibility measurements showed that the magnetic interaction in [Gd(5-Br-NIC)3(H2O)2]2 (2), is antiferromagnetic (J = −0.048 cm−1), while compound [Sm(NIC)3(H2O)2]2 (3), showed a complicated low-temperature magnetic property. 相似文献
106.
Mishra AK Prajapati RK Verma S 《Dalton transactions (Cambridge, England : 2003)》2010,39(42):10034-10037
This communication explores the effect of varying substituent bulk at the N9 position of the adenine moiety and its effect in dictating the structural aspects of silver-adenine frameworks. While adenine alone or 9-benzyl substituted ligand afforded mono and dinuclear dimeric entities, n-propyl substitution at the N9 position results in the formation of a metallaquartet. Longer n-alkyl chains (hexyl and nonyl) resulted in the formation of linear polymeric chains, via N1 and N7 coordination. 相似文献
107.
Non-resonant molecular fragmentation of n-propyl benzene with femtosecond laser pulses is dependent on the phase and polarization
characteristics of the laser. We find that the effect of the chirp and polarization of the femtosecond pulse when applied
simultaneously is mutually independent of each other, which makes chirp and polarization as useful ‘logic’ implementing knobs. 相似文献
108.
Mondal JA Ghosh HN Mukherjee T Palit DK 《The journal of physical chemistry. A》2006,110(44):12103-12112
Ultrafast relaxation dynamics of the S2 and S1 states of 4,4'-bis(N,N-dimethylamino)thiobenzophenone (Michler's thione, MT) have been investigated in different kinds of solvents, using steady-state absorption and emission as well as femtosecond transient absorption and fluorescence up-conversion spectroscopic techniques. Steady-state fluorescence measurements, following photoexcitation to the S2 state of MT, reveal weak fluorescence from the S2 state (phi F approximately 10(-3) in nonpolar and 10(-4) in polar solvents) but much weaker fluorescence from the S1 state. Yield of fluorescence from the S2 state is reduced in polar solvents because of reduced energy gap between the S2 and S1 states, Delta E(S2-S1), as well as interaction with the solvent molecules. Occurrence of S2-fluorescence in polar solvents, despite small energy gap, suggests that symmetry allowed S2(1A1) --> S0 (1A1) radiative and symmetry forbidden S2(1A1) --> S1 (1A2) nonradiative transitions are the factors responsible for the S2 fluorescence in MT. Lifetime of the S2 state is shorter (varying in the range 0.28-3.5 ps in different solvents) than that predicted from the Delta E(S2-S1) value and this can be attributed to its flexible molecular structure, which promotes an efficient intramolecular radiationless deactivation pathways. The lifetime of the S1 state (approximately 1.9-6.5 ps) is also very short because of small energy difference between the S1 and T1 states (Delta E(S1-T1) approximately 300 cm(-1)) in cyclohexane and hydrogen-bonding interaction as well as the presence of the isoenergetic T1(pipi*) state to enhance the rate of the intersystem crossing process from the S1(npi*) state in protic solvents. 相似文献
109.
Feng C Thomas C Holliday MA Tollin G Salerno JC Ghosh DK Enemark JH 《Journal of the American Chemical Society》2006,128(11):3808-3811
Intersubunit intramolecular electron transfer (IET) from FMN to heme is essential in the delivery of electrons required for O2 activation in the heme domain and the subsequent nitric oxide (NO) synthesis by NO synthase (NOS). Previous crystal structures and functional studies primarily concerned an enzyme conformation that serves as the input state for reduction of FMN by electrons from NADPH and FAD in the reductase domain. To favor formation of the output state for the subsequent IET from FMN to heme in the oxygenase domain, a novel truncated two-domain oxyFMN construct murine inducible nitric oxide synthase (iNOS), in which only the FMN and heme domains were present, was designed and expressed. The kinetics of the IET between the FMN and heme domains in this construct was directly determined using laser flash photolysis of CO dissociation in comparative studies on partially reduced oxyFMN and single domain heme oxygenase constructs. 相似文献
110.