Tuning Pt^II‐Based Donor–Acceptor Systems through Ligand Design: Effects on Frontier Orbitals, Redox Potentials, UV/Vis/NIR Absorptions, Electrochromism, and Photocatalysis

Abstract

Asymmetric platinum donor-acceptor complexes [(pimp)Pt(Q 2À )] are presented in this work, in which pimp = [(2,4,6-trimethylphenylimino)methyl]pyridine and Q 2À = catecholate-typed onor ligands. The properties of the complexes are evaluated as af unction of the donor ligands, and correlations are drawn among electrochemical, optical, and theoretical data. Specialf ocus has been put on the spectroelectrochemical investigation of the complexes featuring sulfonyl-substituted phenylendiamide ligands, which showr edoxinducedl inkage isomerism upon oxidation. Time-dependent densityf unctional theory (TD-DFT) as well as electron flux density analysish ave been employedt or ationalize the optical spectra of the complexes and their reactivity.C ompound 1 ([(pimp)Pt(Q 2À )] with Q 2À = 3,5-di-tert-butylcatecholate) was shownt ob ean efficient photosensitizerf or molecular oxygen and was subsequently employed in photochemical cross-dehydrogenative coupling (CDC) reactions. The results thus display new avenues for donor-acceptor systems, including their role as photocatalysts for organic transformations,a nd the possibility to introduce redox-induced linkage isomerism in these compounds through the use of sulfonamides ubstituents on the donor ligands.

Building up PtII−Thiosemicarbazone−Lysine−sC18 Conjugates

“…Importantly, this process is fully reversible; the spectrum of the parent compound (green line in Figure 5) can be fully recovered upon anodic back‐scan. The spectroscopic changes are strongly indicative for a singly reduced pyridine moiety indicating a ligand‐centred reduction, and were thus, fully in line with our DFT calculations and related examples [55–60] …”

“…abundance) pointed to a negligible contribution of Pt orbitals to the singly occupied molecular orbital (SOMO). The g ⊥ and g ‖ values at 2.0066 and 2.0079 supported the ligand centred character [54–58] . At ambient T no signal was observed.…”

Square-Planar Heteroleptic Complexes of α-Diimine-NiII-Catecholate Type: Intramolecular Ligand-to-Ligand Charge Transfer

“…The synergistic existence of donor and acceptor organic parts in the coordination sphere of the metal center is a distinctive feature for a wide range of LL'CT chromophores. The acceptor moiety is usually represented by a neutral redox form of α-diimines (Scheme 1) with significant steric hindrances [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] and/or a rigid carbon skeleton [13,15,[25][26][27]. Thus, it provides the required planarity of the complex's structure.…”

“…Despite such variability of the LL'CT process towards α-diimine-M II -catecholate compounds, there are sporadic works devoted to a targeted molecular design of LL'CT dyes with the primary goal to influence the position and/or intensity of the electronic absorption bands [10,15,[21][22][23][36][37][38], and solvatochromic properties [17,19,22,23,39]. On the other hand, the related square-planar Pd II derivatives are the research objects due to a cytotoxic activity [40][41][42][43].…”

Theoretical investigation on orange-emitting cyclometalated platinum (II) complexes containing organosilyl/organocarbon-substituted 2-(2-thienyl)pyridine ligands

“…Cyclometalated platinum (II) complexes have been extensively studied in the past two decades for use in different domain and application e.g. photoredox catalytic reaction, bioimaging, sensors and as emitters for organic light emitting diodes (OLEDs) [1][2][3][4][5][6][7][8][9]. Platinum (II) and iridium (III) complexes containing 2-phenylpyridyl (ppy) have been widely investigated due to their high luminescence efficiencies and stability [10,11].…”