Pushing Pentacene-Based Fluorescence to the Near-Infrared Region by Platination

Abstract

A series of binuclear platinum complexes of pentacenyl-6,13-diacetylide with different auxiliary ligands were synthesized to probe the effect of metal coordination on electronic spectroscopy and photophysics, to determine the solid-state packing of the complexes, and to tune emission energy. The complexes with anionic, π-donating ligands showed absorption (687−696 nm) and fluorescence (710−726 nm) lower in energy than those with neutral, π-accepting ligands (662−666, 675−686 nm). Our work showed that coordination of Pt ions with π-donating anionic ligands to pentacenyl-6,13-diacetylide could move the fluorescence of the organic chromophore to the nearinfrared region (λ em 710−726 nm). The combined perturbations of alkynation and platination lowered the HOMO → LUMO transition up to 0.34 eV. ■ EXPERIMENTAL SECTIONGeneral Methods. All syntheses were carried out under a N 2 atmosphere. All the solvents used for synthesis and spectroscopic

Single‐Photon Near‐Infrared‐Responsiveness from the Molecular to the Supramolecular Level via Platination of Pentacenes

“…Meanwhile, the LUMO energy levels were −2.316 eV for 1 and −2.710 eV for 3 (Figure 1 b). [Pt(PBu 3 ) 2 I] + perturbs the HOMOs than the LUMOs, due to higher energy matching between the HOMO of 6,13‐dialkynylpentacene and the 5 d orbital of Pt II centers [9b,c] . The calculated HOMO–LUMO gap decreased from 3 (1.90 eV, 652 nm) to 1 (1.85 eV, 670 nm), consistent with the experimental results.…”

Photophysical properties of trans-platinum acetylide complexes featuring N-heterocyclic carbene ligands

“…6,12 Aryl-acetylide ligands have been tuned by altering conjugation length, 6,12 varying the internal and external functionality, 6,[12][13][14] including donor-acceptor motifs, 6 and cross conjugation. 7,15 A square planar platinum(II) complex featuring two aryl-acetylide ligands can adopt either cis and trans geometries; 12 however, the trans configuration is prevalent in the complexes that have been reported. Unlike most platinum acetylides that contain monodentate ligands, bi and tridentate co-ligands use a variety of atoms for bonding to the metal center and altered structural motifs to achieve the desired chelating and electronic effects.…”

A bioinspired sequential energy transfer system constructed via supramolecular copolymerization

“…DFT computations confirm that σ-platination of higher-order acenes render large S 1 –T 1 gaps (S 1 and T 1 denote the lowest singlet excited state and the lowest triplet excited state), and thereby disfavor intersystem crossing due to the Frank-Condon barriers (Supplementary Fig. 10 ) 38 , 39 . Consequently, 1 – 3 exhibit fluorescent emission characters, different from the phosphorescent emission of benzene- and thiophene-substituted dinuclear Pt(II) acetylides (microsecond lifetimes) reported in the previous literature 45 .…”

“…In order to achieve high sequential energy transfer efficiency in the resulting supramolecular copolymers, the elaborate choice of D/A chromophores is of crucial importance. We envisage that σ-platinated (hetero)acenes represent suitable candidates since various acene and heteroacene derivatives can be synthesized with broad spectral coverage 37 – 39 . These σ-platinated acenes are prone to aggregate with each other due to their structural similarity, guaranteeing the proximity of D/A pairs in the resulting supramolecular copolymers 40 – 42 .…”