Department of Chemistry and The Centre for Advanced Materials and Biomaterials Research (CAMBR), The University of Western Ontario, 1151 Richmond Street North, London, Ontario, N6A 5B7, Canada.
Chemistry. 2021 Feb 5;27(8):2854-2860. doi: 10.1002/chem.202004793. Epub 2021 Jan 14.
Near-infrared (NIR) dyes are sought after for their utility in light harvesting, bioimaging, and light-mediated therapies. Since long-wavelength photoluminescence typically involves extensive π-conjugated systems of double bonds and aromatic rings, it is often assumed that NIR dyes have to be large molecules that require complex syntheses. We challenge this assumption by demonstrating that facile incorporation of tertiary amine groups into readily available 3-cyanoformazans affords efficient production of relatively simple NIR-active BF formazanate dyes (λ =691-760 nm, λ =834-904 nm in toluene). Cyclic voltammetry experiments on these compounds reveal multiple reversible redox waves linked to the interplay between the tertiary amine and BF formazanate moieties. Density-functional calculations indicate that the NIR electronic transitions in BF formazanates are of π→π*-type, but do not always involve strong charge transfer.
近红外 (NIR) 染料因其在光收集、生物成像和光介导治疗中的应用而受到关注。由于长波长光致发光通常涉及双键和芳环的广泛 π 共轭体系，因此通常认为 NIR 染料必须是需要复杂合成的大分子。我们通过证明将叔胺基团容易地掺入易得的 3-氰基甲酰腙中，可有效地生产相对简单的 NIR 活性 BF 甲酰腙染料（在甲苯中 λ =691-760nm，λ =834-904nm），从而挑战了这一假设。这些化合物的循环伏安实验揭示了多个与叔胺和 BF 甲酰腙部分相互作用相关的可逆氧化还原波。密度泛函计算表明，BF 甲酰腙中的 NIR 电子跃迁为 π→π*-型，但并不总是涉及强烈的电荷转移。
