Comparative Analysis of the Hydrazine Interaction with Arylene Diimide Derivatives: Complementary Approach Using First Principles Calculation and Experimental Confirmation

Suitable functional group-engineered π-conjugated aromatic dimides based on perylene (PDI) and naphthyl scaffolds (NDI) demonstrated excellent sensitivity toward different gaseous analytes. However, to date, no methodical analysis has been performed to rationalize molecular-level interactions in the context of optical transduction, which is essential for systematic performance optimization of NDI/PDI-based molecular sensors. Therefore, in this present work, NDI/PDI scaffolds have been designed with amino acid functional groups (alanine, ALA and glutamic acid, GLU) at the terminal positions, and we subsequently compared the efficacy of four different imide derivatives as model hosts for hydrazine adsorption. Specifically, the adsorption of hydrazine at different interaction sites has been thoroughly investigated using ab initio calculations, where the adsorption energy, charge transfer, and recovery time have been emphasized. Theoretical results exhibit that irrespective of host specification the COOH groups offer a primary interaction site for hydrazine through the hydrogen bonding interaction. The presence of more COOH groups and relatively stronger interaction with secondary edge oxygen ensure that GLU functional moieties are a superior choice over ALU for efficient hydrazine binding. The molecular energy spectrum analysis exhibits more favorable HOMO/LUMO gap variations after hydrazine interaction in the case of PDI derivatives irrespective to the nature of the amino acid residues. Therefore, by a combination of both factors, PDI-GLU has been identified as the most suitable host molecule for hydrazine among four derivatives. Finally, the key theoretical predictions has been later experimentally validated by analyzing UV-visible spectroscopy and NMR studies, wherein the mechanism of interaction has also been experimentally verified by EPR analysis and FT-IR studies.

Chemical doping of unsubstituted perylene diimide to create radical anions with enhanced stability and tunable photothermal conversion efficiency

N-doping of perylene diimides (PDIs) to create stable radical anions is significant for harvesting photothermal energy due to their intensive absorption in the near-infrared (NIR) region and non-fluorescence. In this work, a facile and straightforward method has been developed to control the doping of perylene diimide to create radical anions using organic polymer polyethyleneimine (PEI) as a dopant. It was demonstrated that PEI is an effective polymer-reducing agent for the n-doping of PDI toward the controllable generation of radical anions. In addition to the doping process, PEI could suppress the self-assembly aggregation and improve the stability of PDI radical anions. Tunable NIR photothermal conversion efficiency (maximum 47.9%) was also obtained from the radical-anion-rich PDI-PEI composites. This research provides a new strategy to tune the doping level of unsubstituted semiconductor molecules for varying yields of radical anions, suppressing aggregation, improving stability, and obtaining the highest radical anion-based performance.

Perylene-Grafted Silicas: Mechanistic Study and Applications in Heterogeneous Photoredox Catalysis

A mechanistic study is herein presented for the use of heterogeneous photocatalysts based on perylene moieties. First, the successful immobilization of perylene diimides (PDI) on silica matrices is demonstrated, including their full characterization by means of electronic microscopy, surface area measurements, powder XRD, thermogravimetric analysis, and FTIR, ²⁹ Si and ¹³ C solid-state NMR, fluorescence, and diffuse reflectance spectroscopies. Then, the photoredox activity of the material was tested by using two model reactions, alkene oxidation and 4-nitrobenzylbromide reduction, and mechanistic studies were performed. The mechanistic insights into their photoredox activity show they have promising dual photocatalytic activity for both organic oxidations and reductions.