A computational study of double perovskites A2BI6 (A = Cs, K, Rb; B = Pt, Sn) invoking density functional theory

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A computational study of double perovskites A2BI6 (A = Cs, K, Rb; B = Pt, Sn) invoking density functional theory

Perovskite materials K2PtI6, K2SnI6, and Rb2SnI6 can be potential candidates for photovoltaic cells. System Cs2SnI6 shows maximum stability among the studied compounds. K2PtI6 with the least value of HOMO-LUMO energy gap displays maximum value of the refractive index and dielectric constant.


Abstract

Lead-free double perovskite materials A2BI6 (A = Cs, K, Rb; B = Pt and Sn) have been studied and analyzed invoking density functional theory (DFT). Computed values of the HOMO–LUMO gap for lead-free double perovskites material A2BI6 are found in the range of 1.062–2.811 eV. The energy gaps of K2PtI6, K2SnI6, and Rb2SnI6 are in the optimal energy gap range (0.9 to 1.6 eV) required for a lead-free double perovskite system. Conceptual DFT-based descriptors, viz., molecular hardness, softness, electronegativity, electrophilicity index, dipole moment, and polarizability, are computed. The result reveals that K2PtI6 shows high efficacy towards electron injection and may show the maximum electron driving force. The optical properties—refractive index and dielectric constant—of these perovskites are also computed. The maximum value of refractive index and dielectric constant is found for K2PtI6. Our computed results are in good agreement with the available experimental and other theoretical data. Perovskite materials K2PtI6, K2SnI6, and Rb2SnI6 display a suitable energy gap as well as a high refractive index and dielectric constant, which makes them suitable for photovoltaic applications.

Synthesis and Chemiexcitation of a Distinct Chemiluminescent Luminophore based on a Curcumin Scaffold

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Synthesis and Chemiexcitation of a Distinct Chemiluminescent Luminophore based on a Curcumin Scaffold


Abstract

Natural fluorogenic dyes are composed of unique molecular structures that could be harnessed for the design of new chemiluminescent luminophores. Here we demonstrated how to simply transform an emissive curcumin scaffold into a novel chemiluminescent luminophore. An appropriate bromo-curcumin intermediate was synthesized as a substrate for a Stille cross-coupling reaction with an adamantyl-stannane reagent. This late-stage functionalization afforded in one step a curcumin enolether precursor that can then be oxidized with singlet oxygen to produce a curcumin chemiluminescent luminophore. This curcumin dioxetane luminophore produced an intense light signal with an emission spectrum that correlates with its curcumin scaffold. This is the first example of a chemiluminescent luminophore that is based on the emissive nature of the curcumin molecular structure. We expect that the method described herein would be useful for the synthesis of new chemiluminescent luminophores by transforming other known emissive dyes into dioxetane precursors via the Stille cross-coupling approach.

5‐Nitrofuryl‐Containing Thiosemicarbazone Gold(I) Compounds: Synthesis, Stability Studies, and Anticancer Activity

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5-Nitrofuryl-Containing Thiosemicarbazone Gold(I) Compounds: Synthesis, Stability Studies, and Anticancer Activity

The stability of new gold(I) containing chloro and biologically active thiosemicarbazones in coordinating and non-coordinating solvents is presented, allowing for a description of potential species formed. The most stable compound (2) results cytotoxic, apoptotic, antimetastatic, and antiangiogenic in a renal cancer cell line like Auranofin but with higher selectivity. 2 accumulates in the nuclei and shows interaction with CT DNA.


Abstract

This work describes the synthesis of four gold(I) [AuClL] compounds containing chloro and biologically active protonated thiosemicarbazones based on 5-nitrofuryl (L=HSTC). The stability of the compounds in dichloromethane, DMSO, and DMSO/culture media solutions was investigated by spectroscopy, cyclic voltammetry, and conductimetry, indicating the formation overtime of cationic monometallic [Au(HTSC)(DMSO)]± or [Au(HTSC)2]±, and/or dimeric species. Neutral [{Au(TSC)}2] species were obtained from one of the compounds in dichlomethane/n-hexane solution and characterized by X-ray crystallography revealing a Au−Au bond, and deprotonated thiosemicarbazone (TSC). The cytotoxicity of the gold compounds and thiosemicarbazone ligands was evaluated against selected cancer cell lines and compared to that of Auranofin. Studies of the most stable, cytotoxic, and selective compound on a renal cancer cell line (Caki-1) demonstrated its relevant antimigratory and anti-angiogenic properties, and preferential accumulation in the cell nuclei. Its mode of action seems to involve interaction with DNA, and subsequent cell death via apoptosis.