Cyclometalated Ir(III) Complexes with Curcuminoid Ligands as Active Second-Order NLO Chromophores and Building Blocks for SHG Polymeric Films

The second-order nonlinear optical (NLO) properties of iridium(III) complexes having two cyclometalated 2-phenylpyridines and curcumin or tetrahydrocurcumin as ancillary ligand have been investigated both in solution and as guest in a polymeric organic matrix. In solution, these complexes are characterized by a significant second-order NLO response, as determined by the Electric Field Induced Second Harmonic (EFISH) technique, like the related complex with acetylacetonate. Whereas the low second-harmonic generation response of a composite film of [Ir(2-phenylpyridine)2(acetylacetonate)] in polymethyl methacrylate was not stable and fell down to zero upon turning off the electric field. A good and stable response was obtained with a film based on the iridium(III) complex bearing two cyclometalated 2-phenylpyridines and curcumin.

Metal-free carbazole scaffold dyes as potential nonlinear optical phores: molecular engineering

In the light of diverse applications of third-order nonlinear optical (NLO) chromophores in interdisciplinary fields, there is high demand for the quest of cost-effective and facile processing of smart materials.

A study on regulating the conjugate position of NLO chromophores for reducing the dipole moment and enhancing the electro-optic activities of organic materials

Adjust the dipole moment of the chromophore by tuning its shape to efficiently transform microscopic nonlinear properties into macroscopic electro-optic activity.

The Progress in the Field Auxiliary Donors and their Application in Novel Organic Second-Order Nonlinear Optical Chromophores

Conversion efficiency between electrical and optical signals is very important for the development of modern information technologies. Due to their advantages in half-wave voltage, bandwidth, cost and integration, as well as organic electro-optic (EO) parameters, these materials are widely studied and used in microwave photonic devices. Second order nonlinear optical (NLO) chromophores, as the core of organic EO materials have an increasing interest in this branch. Auxiliary donors present a new direction for the design and improvement of organic NLO chromophores. In this short review, the advantages, theoretical calculations and experimental results of auxiliary donors are reviewed and discussed in detail.

Electronic Characters and Synthesis Method of Novel Conjugated System Based on Benzodithiophene Groups

Benzodithiophene based conjugated small molecules (SMBDTs) are usually used in organic photovoltaic (OPV), Organic Filed Effection Transistor (OFET), Organic Phototransistor (OPT) and Non-Linear Optical (NLO) chromophores. Band-gap engineering is one of the key design principles for π-conjugated materials and this can be done by altering the structures of SMBDTs with sidechain and backbone reactions. In this way, scientists develop several kinds of SMBDTs with different electron donors and acceptors. The alkoxyl and aromatic substituted BDT units are mostly used as the donors, while the alkyl cyanoacetate, dicyano, rhodamine, indenedione, thieno[3,4-c]pyrrole-4,6(5H)-dione, benzothiadiazole and diketopyrrolopyrrole groups are used as the acceptors. The electronic characters of SMBDTs including the HOMO and LUMO energy level are listed and discussed. The synthesis methods of SMBDTs are mostly in common, especially with the backbone reaction. There are about four coupling methods for the backbone reaction, mostly used is the Stille coupling methods. In this review paper, the common synthesis methods and the electronic characters by several samples are summarized to provide researchers an overview of SMBDTs’ synthesis, structures and applications.

State of the Art of Boron and Tin Complexes in Second- and Third-Order Nonlinear Optics §

Boron and tin complexes have been a versatile and very interesting scaffold for the design of nonlinear optical (NLO) chromophores. In this paper we present a wide range of reports since the 1990s to date, which include second-order (e.g., second harmonic generation) and third-order (e.g., two-photon absorption) NLO properties. After a short introduction on the origin of the NLO response in molecules, the different features associated with the introduction of these inorganic motifs in the organic-based NLO materials are discussed: Their effect on the accepting/donating capabilities of the substituents, on the efficiency of the π-conjugated linkage, and on the topology of the chromophores which can be tuned from the first generation of “push-pull” chromophores to more sophisticated two- or three-dimensional architectures.