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Low-temperature phosphorescence (LTP) and zero-field-splitting (zfs) parameters of the lowest triplet state in zero magnetic field and triplet sublevel dynamics of tryptophan (Trp) residues in alkaline phosphatase (AP), metal-depleted AP (apoAP), and terbium-substituted AP (TbAP) are reported. The results are evaluated to find a plausible mechanism of energy transfer (ET) and TbAP at low temperature.

Research has been conducted on the 4',6-diamidino-2-phenylindol (DAPI) and its complexes. The effect of the local environment on the DAPI triplet state properties has been investigated via the use of phosphorescence and optical detection of magnetic resonance spectroscopy and the results are reported.

Research has been conducted on the alkaline phosphatase tryptophan residues of Escherichia coli. The results of the phosphorescence and zero field optically detected magnetic resonance of these residues are reported.

The nucleocapsid protein of HIV-1 binds to the oligonucleotide stem-loop sequences of the genomic psi-recognition sequences with RNA SL constructs exhibiting higher affinity than corresponding DNA constructs. The stoichiometry of the binding is 2:1 for intact SL sequences and 1:1 for the variant sequences containing an abasic or hydrocarbon loop.

Research describes interactions between proteins and nucleic acids using tryptophan and 6-methyltryptophan aromatic amino acid probes to bind to four peptide-nucleic acid complexes. Data reveal that poly(A), (U), and (I) binding result in large changes in phosphorescence and zero-field splitting parameter in the peptides.

Spin-lattice relaxation (SLR) is studied at 1.2 K in the photoexcited triplet state of tryptophan in a number of protein sites in zero applied magnetic field. The result indicates that there was no correlation of the distribution of populations with the heterogeneity of the protein site as determined by optically detected magnetic resonance bandwidth.

Examines the use of phosphorescence and optical detection of magnetic resonance in determining the triplet state of diamidino-phenyl indole (DAPI). Alteration of biomolecular processes of DNA; Structure of the dication of DAPI; Characterization of DNA complex.

The effects of two ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF 4 ) and 1-butyl-1-methyl pyrrolidinium tetrafluoroborate ([bmp]BF 4 ), on a mixture of phospholipids (PLs) 1,2-dipalmitoyl- sn -glycero-3-phosphatidylcholine (DPPC), 1,2-dipalmitoyl- sn -glycero-3-phosphoethanolamine (DPPE), and 1,2-dipalmitoyl- sn -glycero-3-phosphoglycerol (DPPG) (6:3:1, M/M/M, 70% PL) in combination with 30 mol % cholesterol (CHOL) were investigated in the form of a solvent-spread monolayer and bilayer (vesicle). Surface pressure (π)-area ( A ) isotherm studies, using a Langmuir surface balance, revealed the formation of an expanded monolayer, while the cationic moiety of the IL molecules could electrostatically and hydrophobically bind to the PLs on the palisade layer. Turbidity, dynamic light scattering (size, ζ-potential, and polydispersity index), electron microscopy, small-angle X-ray/neutron scattering, fluorescence spectroscopy, and differential scanning calorimetric studies were carried out to evaluate the effects of IL on the structural organization of bilayer in the vesicles. The ILs could induce vesicle aggregation by acting as a "glue" at lower concentrations (<1.5 mM), while at higher concentrations, the ILs disrupt the bilayer structure. Besides, ILs could result in the thinning of the bilayer, evidenced from the scattering studies. Steady-state fluorescence anisotropy and lifetime studies suggest asymmetric insertion of ILs into the lipid bilayer. MTT assay using human blood lymphocytes indicates the safe application of vesicles in the presence of ILs, with a minimal toxicity of up to 2.5 mM IL in the dispersion. These results are proposed to have applications in the field of drug delivery systems with benign environmental impact.

The absence of d-orbital electrons or presence of full-filled d-orbital electrons in metal ions is a well-known Achilles' heel problem for the detection of these metal ions by a simple UV-visible study. For this reason, detection of metal ions such as Al 3+ with no d-orbital electrons or Zn 2+ with filled d-orbital electrons is a challenging task. Herein, we report a 2-naphthol-based fluorescent probe [1-(( E )-(( E )-(5-bromo-2-hydroxybenzylidene)hydrazono)methyl)naphthalen-2-ol] ( H 2 L ) that has been used to sense and discriminate Al 3+ and Zn 2+ via solvent regulation. The probe exhibits excellent selectivity and swift sensitivity toward Al 3+ in MeOH-water (9:1, v/v) and toward Zn 2+ in dimethyl sulfoxide (DMSO)-water (9:1, v/v) among various metal ions. The respective detection limit is found to be 9.78 and 3.65 μM. The sensing mechanism is attributed to multiple processes, viz., the inhibition of photo-induced electron transfer (PET) along with the introduction of chelation-enhanced emission (CHEF) and excited-state intramolecular proton transfer (ESIPT) inhibition, which are experimentally well verified by UV-vis absorption spectroscopy, emission spectroscopy, and NMR spectroscopy. The probe shows aggregation-induced emissive (AIE) response in ≥70% aqueous media as well as in the solid state. The experimental results are well corroborated by time-resolved photoluminescence (TRPL) and density functional theory (DFT) calculations. An advanced-level OR-AND-NOT logic gate has been constructed from a different chemical combinational input and emission output. The reversible recognition of both Al 3+ in MeOH-water (9:1, v/v) and Zn 2+ in DMSO-water (9:1, v/v) is also ascertained in the presence of Na 2 EDTA, enabling the construction of a molecular memory device. The probe H 2 L also detects intracellular Al 3+ /Zn 2+ ions in Hela cells. Altogether, our fundamental findings will pave the way for designing and synthesis of unique chemosensors that could be used for cell imaging studies as well as constructing molecular logic gates.