Tuning of optical properties of p-phenyl ethenyl-E-furans: A Solvatochromism and Density functional theory

Recent Development on Copper-Sensor and its Biological Applications: A Review

Metal ion recognition is one of the most prospective research topics in the field of chemical sensors due to its wide range of clinical, biological and environmental applications. In this context, hydrazones are well known compounds that exhibit metal sensing and several biological properties due to the presence of N=CH- bond. Some of the biological properties includes anti-cancer, anti-tumor, anti-oxidant, anti-microbial activities. Hydrazones are also used as a ligand to detect metal ion as well as to generate metal complexes that exhibit medicinal properties. Thus, in recent years, many attempts were made to develop novel ligands with enhanced metal sensing and medicinal properties. In this review, some of the recent development on the hydrazones and their copper complexes are covered from the last few years from 2015-2023. These includes significance of copper ions, synthesis, biological properties, mechanism and metal sensing properties of some of the copper complexes were discussed.

Antiradical Properties of trans-2-(4-substituted-styryl)-thiophene

2-substituted thiophene compounds with electron donating and electron withdrawing p-phenyl substitution were synthesized and studied their radical scavenging properties using DPPH assay and DFT method. It is shown that p-hydroxy and p-amino phenyl substituted compound exhibit radical scavenging activity. From DFT and radical scavenging studies, a correlation between IC₅₀ with the bond dissociation enthalpy, proton affinity, ground state dipole moment and optical band gap of compound is found. Compounds 1-3 with electron withdrawing substituent (NO₂, CN, Cl) do not show any radical scavenging properties, whereas compounds 6-7 with electron donating substituent (OH, NH₂) show antiradical properties. Further, the antiradical activity is reduced drastically by replacing the -OH and -NH₂ with methoxy and -N-alkylating group respectively in 6 and 7. The compound with p-hydroxy phenyl substitution, exhibits stronger antiradical activity as compared to the p-amino phenyl substitution due to smaller O-H bond dissociation energy as compared to the N-H bond. From DPPH and DFT studies, it is suggested that the radical scavenging activity in 2-substituted thiophene is occurred through proton transfer mechanism. The other possible SET, SPLET mechanisms are also corroborated. Graphical Abstract Antiradical properties of trans-2-(4-substituted-styryl)-thiophene Anamika Gusain, Naresh Kumar, Jagdeep Kumar, Gunjan Pandey, Prasanta Kumar Hota.

Optical properties of 3-substituted indoles

The optical properties of various donor or acceptor p-phenyl substituted ethenyl indoles were studied in solvents of varying polarity using absorption, fluorescence and TDDFT methods. Ethenyl indole exhibits non-linear optical properties (NLO) in a substituent dependent manner. Compound with a strong electron-attracting substituent, shows large NLO properties with charge transfer behavior, whereas ethenyls with moderate electron withdrawing or electron donating substituent exhibit lower NLO properties with non polar excited state. A highly dipolar excited state for p-nitro phenyl substituted ethenyl indoles (μ _e: 18.2-27.1 debye; Δμ: 9.4-17.8 debye) is observed as compared to other ethenyls (μ _e: 6.6-9.5 debye; Δμ: 4.2-6.2 debye). From TDDFT study, it is shown that the HOMO-LUMO energy of ethenyl is increased with increasing the electron donating ability of the p-phenyl substitution. The optical band gap of ethenyl 3 without substitution, is decreased upon p-phenyl substitution either with an electron withdrawing (Cl, NO₂) or an electron donating (OCH₃, OH, NH₂) substituent. The compound with a strong electron accepting, p-nitrophenyl ethenyl indole 1 shows 12 times better NLO response as compared to the reference ethenyl indole 3 (β: 1: 115 × 10^-30 esu^-1 cm⁵, 3: 9 × 10^-30 esu^-1 cm⁵). Ethenyls 2-6 bearing a weak or moderately electron withdrawing or electron accepting substituent, exhibit lower NLO response. The β of ethenyl is increased with increasing the order of electron withdrawing nature of phenyl ring. Overall, a correlation of β with the optical band gap, ground state dipole moment, % of charge transfer in the ground and excited state is found.

Antioxidant properties of ethenyl indole: DPPH assay and TDDFT studies

Ethenyl indole exhibits antioxidant activity in a substituent dependent manner. Ethenyls bearing strong electron withdrawing substituents show weak or no antioxidant activities, whereas ethenyls with electron donating substituents exhibit antioxidant properties comparable to vitamin E.

Surface modification strategy for fluorescence solvatochromism of carbon dots prepared from p-phenylenediamine

Surface modification of p-phenylenediamine-derived carbon dots with decanoic acid and perfluorodecanoic acid successfully modulated fluorescence solvatochromism.