Merocyanines: Electronic Structure and Spectroscopy in Solutions, Solid State, and Gas Phase

Merocyanines, owing to their readily tunable electronic structure, are arguably the most versatile functional dyes, with ample opportunities for tailored design via variations of both the donor/acceptor (D/A) end groups and π-conjugated polymethine chain. A plethora of spectral properties, such as strong solvatochromism, high polarizability and hyperpolarizabilities, and sensitizing capacity, motivates extensive studies for their applications in light-converting materials for optoelectronics, nonlinear optics, optical storage, fluorescent probes, etc. Evidently, an understanding of the intrinsic structure-property relationships is a prerequisite for the successful design of functional dyes. For merocyanines, these regularities have been explored for over 70 years, but only in the past three decades have these studies expanded beyond the theory of their color and solvatochromism toward their electronic structure in the ground and excited states. This Review outlines the fundamental principles, essential for comprehension of the variable nature of merocyanines, with the main emphasis on understanding the impact of internal (chemical structure) and external (intermolecular interactions) factors on the electronic symmetry of the D-π-A chromophore. The research on the structure and properties of merocyanines in different media is reviewed in the context of interplay of the three virtual states: nonpolar polyene, ideal polymethine, and zwitterionic polyene.

Construction of a simple crosslinking system and its influence on the poling efficiency and oriental stability of organic electro-optic materials

A new fluorinated polycarbonate was synthesized by solution polymerization of bisphenol AF, anthracen-9-ylmethyl-4,4-bis(4-hydroxyphenyl)pentanoate with triphosgene. This new polycarbonate was used as a host polymer. A traditional chromophore with a D–π–A structure was modified by bisphenol A acrylate affording chromophore A. The large modified group can not only effectively avoid the dipole interaction between chromophores, but also endow the chromophores with the properties of attaching and crosslinking with a host polymer through in situ Diels–Alder “click chemistry” reactions. Such properties can improve both the poling efficiency and the thermal stability of organic electro-optic (EO) polymers. The thermodynamic properties of the crosslinking system showed that the glass transition temperature rose with the increase of the chromophore content. The EO polymer showed a large EO coefficient of about 78.9 pm V⁻¹ at a wavelength of 1310 nm and an excellent long-term stability of about 89% with respect to its initial value and it can be kept after 300 h of heating at 80 °C.

A new fluorinated polycarbonate was synthesized by solution polymerization of bisphenol AF, anthracen-9-ylmethyl-4,4-bis(4-hydroxyphenyl)pentanoate with triphosgene.

Synthesis of asymmetric dendrimers with controllable chromophore concentration and improved electro-optical performance

In this work, we provided a simple work-up procedure to prepare a new kind of electro-optical dendrimer with an asymmetric configurationviaa Cu-(i) catalyzed Huisgen-reaction.

Research of the optimum molar ratio between guest and host chromophores in binary chromophore systems for excellent electro-optic activity

A series of binary chromophore systems were designed and prepared. The optimum molar ratio (OMR) between guest and host chromophores was first systematically explored in the BCSs. When at the OMR, there is the biggest EO coefficient growth rate.

Asymmetric dendrimers with improved electro-optic performance: synthesis and characterization

A new series of electro-optical dendrimers with asymmetric configurations was synthesized through a Cu-(I) catalyzed Huisgen reaction.