Advances in Polymethine Dyes for Near-Infrared Organic Photodiodes

Near-infrared organic photodiodes (NIR OPDs) have tremendous potential in industrial, military, and scientific applications, due to their unique features of lightweight, low toxicity, high structural flexibility, cooling-system-free, etc. However, the overall performance of currently available NIR OPDs still lags behind the commercial inorganic photodetectors, ascribed to the critical challenge of realizing organic semiconductors with sufficiently low optical bandgap and excellent optoelectronic properties simultaneously. Among various types of NIR-absorbing organic semiconductors, polymethine dyes not only possess advantages of simple synthesis and structural diversity, but also show fascinating optical and aggregation features in the solid state, making them attractive material candidates for NIR OPDs. In this review, after a brief introduction of NIR OPDs and polymethine dyes, we comprehensively summarize the advances of polymethine dyes for broadband and narrowband NIR OPDs, and further introduce their applications in all-organic optical upconversion devices and photoplethysmography sensors. In particular, the relationship between the chemical structure and the aggregation behaviors of polymethine dyes and the device performance is carefully discussed, providing some important molecular insights for developing high performance NIR OPDs.

A general approach to the design of high-performance near-infrared (NIR) D-π-A type fluorescent dyes

Near infrared(NIR) absorbing and emitting dyes are sought after for their potentials in bioimaging and theranostic applications. They are typically not as stable as dyes absorbing and emitting in the visible spectral range, as the result of a reduced HOMO-LUMO band-gap. Also, they are not as efficient fluorescence emitters due to accelerated internal conversion kinetics. In addition, their large conjugative backbone render them high tendency to form aggregate and low aqueous solubility. In this tutorial, we have described a four-step approach for rational design of organic dyes with an overall high-performance to meet the rigorous requirements of biological applications. Also, some background regarding "NIR" is provided along with some recent breakthroughs of the field.

Molecular docking of cyanine and squarylium dyes with SARS-CoV-2 proteases NSP3, NSP5 and NSP12

Background:The outbreak and continued spread of coronavirus infection(COVID-19)sets the goal of finding new tools and methods to develop analytical procedures and tests to detect,study infection and prevent morbidity.Methods:The noncovalent binding of cyanine and squarylium dyes of different classes(60 compounds in total)with the proteases NSP3,NSP5,and NSP12 of SARS-CoV-2 was studied by the method of molecular docking.Results:The interaction energies and spatial configurations of dye molecules in complexes with NSP3,NSP5,and NSP12 have been determined.Conclusion:A number of anionic dyes showing lower values of the total energy Etot could be recommended for practical research in the development of agents for the detection and inactivation of the coronavirus.