Impact of 2,6-connectivity in azulene: optical properties and stimuli responsive behavior

Abstract

The possible incorporation of the redox active, small donor acceptor molecule azulene as a core structure for potential optoelectronic applications has been evaluated. The synthesis and characterization of different isomers of di(phenylethynyl)azulene 1-4 have been successfully carried out. The photophysical properties as well as their stimuli responsive behavior reflecting their corresponding electronic properties were also investigated. The experimental observations show that 2,6-connection (3) exhibits intense luminescence and shows the strongest stimuli responsive behavior upon acid treatment. DFT calculations of 3 reveal the highest contributions of the alkyne substituents at the 2-and 6-position of the azulene to the ground-and excited state that makes the 2,6-connectivity at azulene a very promising candidate for low band-gap conjugated materials.

(Azulene‐1,3‐diyl)‐bis(nitronyl nitroxide) and (Azulene‐1,3‐diyl)‐bis(iminonitroxide) and Their Copper Complexes

“…Reagents and general procedures 4,4,5,5-Tetramethyl-4,5-dihydro-1H-imidazol-3-oxid-1-oxyl, [23,24] (nitronyl nitroxide-2-ide)(triphenylphosphine)gold, [9] and 1,3-diiodoazulene [25] were synthesized as reported earlier.Cu(hfac) 2 [26] was sublimed before use. THF was freshly distilled over sodium hydride.…”

Chromophoric materials derived from a natural azulene: syntheses, halochromism and one-photon and two-photon microlithography

“…3,8 Among known natural pigments, 6-8 guaiazulene has received recent popularity for its interesting physical and electronic properties. [28][29][30][31][32][33] This reversible behavior has led to the use of azulene as a 3 modular building block for the construction of conducting polymers, 6 as cathode modification layers in bulk-heterojunction solar cells, 26 and in electrochromic and nonlinear optical materials. [9][10][11][12][13][14][15][16] Chemically, guaiazulene is a nonalternant hydrocarbon that is notable for its low transition energy to the S 1 state and unusually large S 1 -S 2 gap, [17][18][19][20][21][22][23][24][25][26][27] where S 1 and S 2 refer to the first and second electronically excited states, respectively.…”

Computer aided chemical design: using quantum chemical calculations to predict properties of a series of halochromic guaiazulene derivatives

“…The unique electronic properties of azulene-based structures were instrumental in the development of derivatives for charge-transport, optoelectronic and sensor applications. The design of such structures is often based on theoretical calculations of the dipole moment of azulene derivatives; variation in calculated dipole moments is thought to be a result of various substituents on the azulene framework that acts as an electron bridge in a donor–acceptor–donor arrangement [12,15,16]. While these calculations predict a large dipole moment and large hyperpolarizability for 2,6-connected azulene systems, experimental investigation shows that a 4,7-connectivity often results in longer absorption and emission wavelengths, a desirable property for the development of various near-IR applications [10].…”