Synthesis and Computational Study of Semicroconaines and Nonsymmetric Croconaines

Abstract

The synthesis of two new dye families of croconic acid derivatives, semicroconaine and nonsymmetric croconaine dyes, is reported for the first time. These compounds show strong absorption in the UV−visible and NIR, respectively. Semicroconaine dyes were obtained by a scalable and efficient condensation of croconic acid with aromatic heterocyclic methylene-active compounds. The subsequent reaction of the semicroconaine dyes with aromatic heterocyclic compounds affords nonsymmetric croconaines. The structure and electronic properties of the synthesized compounds have been investigated by preliminary theoretical calculations at DFT level of approximation.

Peripherical thioester functionalization induces J-aggregation in bithiophene-DPP films and nanoparticles

“…Although processing conditions play a key role in the solid-state arrangement of organic semiconductors in thin lm, 1 chemists are attracted by the possibility to control the organization of conjugated molecules by the structural design. [2][3][4][5] In this context, it is particularly interesting the case of diketopyrrolo [3,4.c]pyrrole (DPP) derivatives. DPPs are gaining a prominent position among organic dyes for optics and electronics thanks to their simple synthesis, intense color, high photostability, and good charge transport properties.…”

Solvent‐free Reactions for the Synthesis of Indolenine‐based Squaraines and Croconaines: Comparison of Thermal Heating, Mechanochemical Milling, and IR Irradiation

“…In particular, comparable yields were obtained in the presence of Na 2 SO 4 (53 %, Table 2, entry 10) or montmorillonite K10 (51 %, Table 2, entry 12), while yield as high as 64 % (Table 2, entry 11) was obtained in the presence of NaCl. The mechanochemical approach was also investigated for the synthesis of non‐symmetric croconaine 3 starting from the semicroconaine S2 [2b] and the 2,3,3‐trimethylindolenine 1I (Table 3). The reaction of S2 and 1I in 1 : 2 molar ratio produced the non‐symmetric croconaine 3 in 46 % yield (Table 3, entry 1) after 3 h of milling.…”

“…[b] Isolated yield. [c] Literature yields for conventional protocols in solution: 1 (60 %), [2a] 2 (64 %), [10] 3 (70 %), [2b] 4 (75 %), [11a] 5 (57 %) [11b] . [d] Optimized conditions.…”

“…Reagents and solvents were purchased at the highest commercial purity from Sigma‐Aldrich and TCI Europe and used without further purification. 5‐((1,1‐Dimethyl‐1 H ‐benzo[e]indol‐3‐ium‐2‐yl)methylene)‐2‐hydroxy‐3,4‐dioxocyclopent‐1‐enolate was prepared according to our previously reported procedure [2b] . Montmorillonite K10 clay was dried at 180 °C for 4 h before use.…”

Croconaine Rotaxane Dye with 984 nm Absorption: Wavelength‐Selective Photothermal Heating

“…This report describes an advance in our work on croconaine dyes, an emerging near‐infrared chromophore system that is gaining increasing attention for various sensing, photothermal, optoelectronic, and photoacoustic applications . In 2013, we showed that croconaine dyes, such as C1 (Scheme ), are very useful as near‐infrared photothermal agents, and in the subsequent time period we and others have shown that they can be used for clean photothermal heating of nanoparticles without producing singlet oxygen, photothermal switching of polymer morphology,, and laser ablation of tumors in living animals , .…”