Ravi Kumar Kanaparthi

By Ravi Kumar Kanaparthi, Satyen Saha, Manjeev Singh and Akhila M

4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) is, commonly known as red dye, an electron donor-acceptor molecule that exhibits very interesting photophysical properties such as high molar absorption coefficients, tunable electronic absorption and fluorescence emission energies, and high fluorescence quantum yields. Several DCM analogous have been synthesized and explored for various practical applications that include solid-state lasers, organic light-emitting diode (OLED), fluorescent sensors, logic gates, photovoltaics, nonlinear optics (NLO), and bioimaging of cells. In recent years, a significant amount of research work has been devoted for developing optical sensors based on DCM dye for detection of various guest analytes. The first part of this book chapter describes comprehensive photophysical properties of the DCM dye which include the results of steady-state and time-resolved absorption and fluorescence studies. The second part of the book chapter summarizes the recent developments of DCM-based optical sensors that exhibit colorimetric, ratiometric, and fluorosensing towards selective detection of metal cations, anions, and neutral species.

Part of the book: Photophysics, Photochemical and Substitution Reactions

By Krishanu Bandyopadhyay, Abhineet Verma, Tamal Ghosh, Ravi Kumar Kanaparthi, Sudeena Nadendla and Satyen Saha

This chapter discusses the significant impact of N-heterocyclic carbene (NHC) ligands on the optical properties of metal complexes. It highlights the key role of NHC ligands in shifting the d−d transitions of these complexes to shorter wavelength regions, rendering them luminescent. The study focuses on NHC-based metal complexes involving copper, silver, platinum, iridium, and coinage metals, showcasing their luminescent properties and potential applications in organic light-emitting diodes (OLEDs). However, it also underscores a challenge: the quantum yields of these metal complexes may not be sufficient for practical applications. To address this issue, this chapter proposes modifying the NHC ligand with electron-rich substituents, aiming to reduce the HOMO-LUMO gap and shift d-d transitions into the UV region. Additionally, it introduces cyclic (alkyl)(amino)carbene (CAACs) as promising ligands for tuning the photophysical properties of metal complexes. CAACs are noted for their ability to decrease the HOMO-LUMO gap compared to NHCs and their electrophilic nature. Luminescent CAAC metal complexes are found to exhibit sub-microsecond lifetimes, making them suitable candidates for OLED applications. Ultimately, the research challenges researchers to better understand the structure, bonding, and properties of these complexes to create stable and highly luminescent materials using abundant and cost-effective metals like iron, copper, zinc, and silver.

Part of the book: Revolutionizing Energy Conversion - Photoelectrochemical Technologies and Their Role in Sustainability [Working title]