Synthesis and characterization of novel diazenes bearing pyrrole, thiophene and thiazole heterocycles as efficient photochromic and nonlinear optical (NLO) materials

Abstract

Two series of novel thermally stable second-order nonlinear optical (NLO) and photochromic chromophores have been designed and synthesized. The two series of compounds were based on different combinations of donor groups (pyrrole or thienylpyrrole) which act simultaneously as -conjugated bridges, together with diazoaryl or diazothiazolyl as acceptor moieties. Their photochromic and electrochemical behavior were characterized, while hyper-Rayleigh scattering (HRS) was employed to evaluate their second-order nonlinear optical properties. The results of these studies have been critically analyzed together with two other related compounds reported earlier from our laboratories in which the thienylpyrrole system was used as the donor group keeping the functionalized diazoaryl as acceptor moiety.The measured molecular first hyperpolarizabilities and the observed photochromic behavior showed strong variations for the different donor systems used (pyrrole or thienylpyrrole) and were also sensitive to the acceptor strength of the diazenehetero(aryl) moiety.The thienylpyrrole based compounds endowed with extended -conjugated bridges and stronger donor auxiliary effects in comparison to the pyrrole compounds, when coupled to the stronger acceptor diazo(hetero)aryl groups gave rise to significantly larger hyperpolarizabilities ( = 274 -415 x 10 -30 esu) for an incident wavelength of 1064nm). These compounds also displayed improved photochromic behavior with very fast response to the visible light stimulus (1.5 s) and fast thermal return to the original forms (2-3 s).

Highly efficient and thermally stable NLO organic materials based on pyrrole and thiophene heterocycles

“…spectra is observed when stronger acceptor groups are linked to the heterocyclic system. [8][9][10][11][12][19][20] As a result the substitution of a formyl group for a 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile moiety leads to a red shift of 170 nm from 348 nm (1a) to 510 nm (1e). Within the series 1a-e the CT bands moves to lower energy as the electron accepting ability of the acceptor moiety increases, in the order CHO < dicyanovinyl < rhodanine < thiobarbituric acid < 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile (Fig.…”

Transition metal-free one-pot synthesis of nitrogen-containing heterocycles

“…For example, five-membered heterocycles are present in more than hundred drugs available in the market and approximately thousands of heterocyclic derivatives are under clinical trials [37]. Apart from this, they have also been known for their catalytic [38,39], fluorescent [40][41][42], and dying properties [43,44].…”

New Insight into the Synthesis of Aromatic Azo Compounds Assisted by Surface Plasmon Resonance

“…With the -N = N-bond and the unique structure of a large π electronic system, aromatic azo compounds can be freely and reversibly inter-converted between cis and trans configurations [10]. The characteristics and good photochromic performance of aromatic azo compounds make them suitable for a wide range of potential applications in the field of modern high-technology, such as nonlinear optoelectronic information materials [11], chemical sensors [12], liquid-crystal materials [13,14], photochemical molecular switches [15,16], bioluminescent imaging agents [17], molecular machines [18], nanotubes [19], protective glass filters [20], and energetic materials [21].…”