Solvent Effects on Intra-/Intermolecular Charge Transfer in Indoloquinoxaline-Based Dyes

6H-Indolo-[2,3-b]-quinoxaline derivatives as promising bifunctional SHP1 inhibitors

Dysfunction in the SHP1 enzyme can cause cancers and many diseases, so it is of great significance to develop novel small molecule SHP1 inhibitors. Through continuous monitoring of metabolic and targeted processes of SHP1 inhibitors in real-time, we can evaluate the effectiveness and toxicity of the inhibitors, further optimize drug design, and explore SHP1 biology. Indoloquinoxaline is an important class of N-containing heterocycle, which has been studied and applied in the pharmacological field and in optoelectronic materials. In this work, the potential Src homology 2 domain-containing phosphatase 1 (SHP1) inhibitor 5a was developed with the help of the structural fusion and scaffold hop of a fluorophore, 6H-indolo-[2,3-b]-quinoxaline, and a bio-active skeleton, thieno[2,3-b]quinoline-procaine. Compound 5a selectively inhibited the SHP1PTP enzyme abilities (IC50 = 2.34 ± 0.06 μM), exhibited a significant fluorescence response (P = 0.007) in response to SHP1PTP activity, and emitted strong blue/green fluorescence in MDA-MB-231 cells. Furthermore, compound 5a showed irreversible binding with SHP1PTP in simulations and dialysis experiments. Altogether, compound 5a serves as a bifunctional SHP1 inhibitor, combining imaging and therapeutic functionalities, enhancing our understanding of SHP1 biological mechanisms, and positively impacting novel drug development.

Role of Explicitly Included Solvents on Ultrafast Electron Injection and Recombination Dynamics at TiO2/Dye Interfaces

Solvent effects are important for photovoltaic systems like dye-sensitized solar cells (DSCs) but remain largely unexplored, partly due to the complexity of explicitly including solvent molecules in atomistic simulations. To address these issues, we have systematically investigated the solvent effects in practical solar cells using ab initio excited state dynamics simulations. In this computational protocol and the extended model system, we considered giving a novel perspective on the excited state changes in response to solvation and finite temperature at the heterointerface of DSCs. By directly comparing the geometric stability of interface bonding, photoabsorption, interfacial electronic structure, and dynamics of vacuum and solvent systems, we obtain useful insights into how solvents influence the key factors that determine the efficiency of DSCs. Solvents significantly enhance the intensity of visible light absorption of chromophores (∼2 times) through two effects: (a) by inducing changes to the dye molecule structure due to intermolecular dye-solvent interactions, and (b) by the dielectric screening of the solvent. Furthermore, by adsorbing onto the TiO₂ surface, solvent molecules adjust the interfacial band alignment to a favorable level and screen out the attraction force between injected electrons in the semiconductor substrate and holes left on the chromophore to a large extent, dramatically slowing down the recombination process (>8 times). Our findings provide a comprehensive picture of the explicit solvent effects on individual energy conversion steps in DSCs at the microscopic scale and lead to more accurate prediction of the performance of nanodevices in practical environments, contributing to the optimization of realistic renewable energy devices.