Tunable solvatochromic response of newly synthesized antioxidative naphthalimide derivatives: intramolecular charge transfer associated with hydrogen bonding effect.
ABSTRACT The solvatochromic behavior of two newly synthesized naphthalimide derivatives (I and II) which have potential antioxidative activities in anticarcinogenic drug development treatment, has been monitored in protic and aprotic solvents of different polarity applying steady-state and time-resolved fluorescence techniques. The compounds exhibit unique photophysical response in different solvent environments. The spectral trends do not appear to originate only from changes in the solvent polarity but also indicate that hydrogen bonding interactions and intramolecular charge transfer (ICT) influence the energy of electronic excitation of the compounds. Incorporation of an amino group at C(4) position of the naphthalimide ring in II makes it behave differently from I in terms of spectral characterization and fluorescence efficacy of the systems. The nonradiative relaxation process of the compounds is governed by medium polarity. The ground state geometry, lowest energy transition, and the UV-vis absorption energy of the compounds were studied using density functional theory (DFT) and time-dependent density functional theory (TDDFT) at the B3LYP/6-31G* level, which showed that the calculated outcomes were in good agreement with experimental data.
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ABSTRACT: A series of imidazole derivatives connected with pyridine moiety through phenyl groups were synthesized by using Suzuki coupling followed by multicomponent cyclization reaction. Results obtained from spectroscopic ((1)H NMR, (13)C NMR, Mass) and single crystal X-ray diffraction analysis of synthesized compound was in very good agreement with its chemical structure. UV-Vis and fluorescence studies in various solvents with different polarity demonstrated that these compounds were sensitive to the polarity of the microenvironment. In addition, multi linear regression analysis based on Kamlet-Taft and Catalán new four parameter solvent scale results in solvatochromism and was mainly influenced by solvent polarisability and dipolarity of the environment. The electrochemical stability of the compounds was also studied by cyclic voltammetry. An excellent fluorescent nature with high quantum efficiency of the compounds was successfully utilized to probe the bacteria by using fluorescence microscopy. In addition, the antibacterial and antifungal activity of these compounds were also studied in vitro by the disk diffusion assay against one Gram-positive, three Gram-negative bacteria and Candida albicans. MPBI showed relatively good inhibitory action against Gram-negative bacteria and TPBI against Gram-positive bacteria and 3PBI against C. albicans.Journal of photochemistry and photobiology. B, Biology 09/2013; 127C:212-222. · 3.11 Impact Factor
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ABSTRACT: Fluorescence recognition and sensing of aqueous anionic species is a challenging task and is being increasingly appreciated as far as potential biological and environmental issues of such systems are concerned. In the present contribution, we introduce for the first time fluorescence amplified recognition of a naphthalimide derivative (NAP) being embedded in a cationic alkyl trimethyl ammonium bromide micellar (CnTAB) units by various anions applying steady state and time resolved fluorescence techniques. Strongly quenched NAP emission in micellar framework has been effectively recovered upon intervention of various anions (such as H2PO4−, HPO42−, PO43−, SO42−, Cl−, etc.) with different sensitivities. The sensing process based on ion displacement mechanism, which principally governs a proficient fluorescence enhancement to various anions in a simple and efficient way, has been demonstrated. Optimization of sensor is achieved by altering surfactant chain length. The intermolecular approach used here seems to be rather flexible and appealing to design interface oriented fluorescent sensors to convene different analytic purposes for a wide variety of anion targets.Sensors and Actuators B: Chemical. 176:467–474.
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ABSTRACT: The principal intent of the present contribution is to decipher the binding domain and structural changes of trypsin (TPS), a proteolytic globular enzyme and two serum proteins, namely, bovine serum albumin (BSA), human serum albumin (HSA) association with a newly synthesized bioactive isoquinolindione derivative (ANAP) by employing steady state, time resolved fluorescence and circular dichroism (CD) techniques. Intramolecular charge transfer emission (ICT) of ANAP is found to be responsible for the commendable sensitivity of the probe as an extrinsic fluorescent marker to the protein environments. A sharp distinctive feature of determined micropolarities in proteinous media clearly demarcates the differential extent of hydrophobicity around the encapsulated ANAP. A proficient efficiency tunable fluorescence (Förster type) resonance energy transfer (FRET) from the excited tryptophan to ANAP reveals that ANAP binds in the close vicinity of the tryptophan residue in protein. Molecular modeling simulation has been exploited for evaluating the probable interaction site of ANAP in proteinous assembly which shows subdomain IIA are earmarked to possess affinity for ANAP in serum albumins whereas S1 binding pocket in TPS has been found potential binding region for ANAP.Journal of photochemistry and photobiology. B, Biology 10/2013; 129C:69-77. · 3.11 Impact Factor