Thermal cis-to-trans isomerisation of triazene dyes in doped polymer films

Tabone, Ryan; Barra, Mónica

doi:10.1016/j.dyepig.2010.06.006

Cited by 12 publications

(8 citation statements)

References 37 publications

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“…Applying a biexponential kinetics ( 3 ) the thermal relaxation of the cis-isomer in film can be described using our experimental data and a value of 0.18 was obtained for α. Deviations from a first-order kinetics are generally determined by the inhomogeneous distribution of local free volume in polymer matrix [ 33 , 34 ]. The bimodal kinetics observed for thermal cis-trans isomerization of azobenzenes chromophores in polymer films can be interpreted as being due to the trapping of some of cis-isomers in a strained conformation which isomerize more rapidly to the trans state than the relaxed cis remaining isomers [ 33 , 35 ]. The two rate constants for ABM 2 in PMMA films were (7.68 ± 0.14) × 10 −5 and (5.00 ± 0.06) × 10 −5 s −1 , respectively at 50 °C.…”

Section: Resultsmentioning

confidence: 99%

Optical Properties of Some New Azo Photoisomerizable Bismaleimide Derivatives

Airinei¹,

Fifere²,

Homocianu³

et al. 2011

IJMS

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Novel polythioetherimides bearing azobenzene moieties were synthesized from azobismaleimides and bis-2-mercaptoethylether. Kinetics of trans-cis photoisomerization and of thermal conversion of cis to trans isomeric forms were investigated in both polymer solution and poly(methyl methacrylate) doped films using electronic absorption spectroscopy. Thermal recovery kinetics is well described by a two-exponential relation both in solution and polymer matrix, while that of low molecular weight azobismaleimide fit a first-order equation. The photoinduced cis-trans isomerization by visible light of azobenzene chromophores was examined in solution and in polymer films. The rate of photoinduced recovery was very high for azobismaleimides.

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Section: Resultsmentioning

confidence: 99%

Optical Properties of Some New Azo Photoisomerizable Bismaleimide Derivatives

Airinei¹,

Fifere²,

Homocianu³

et al. 2011

IJMS

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“…Longer irradiation or performing the isomerization at −30 °C did not change the isomer ratio, suggesting the photo‐stationary state had been reached. Similar light‐induced E ‐to‐ Z isomerization across the N=N bond was observed with triazenes derived from cyclic amines, such as Ph−N=N−NR 2 (R 2 =cyclic moiety) [34,47] . The kinetics of thermal E ‐to‐ Z isomerization of triazenes was shown to proceed via an internal rotation mechanism involving heterolytic N=N π bond rupture and subsequent twisting around the C−N=N−N dihedral angle [47] …”

Section: Resultsmentioning

confidence: 67%

“…They are well known in organic synthesis [25,26] for heterocycle formation, [27,28] functional group generation [29,30] and amine protection [31] . Their photochemical properties have also led to application as dyes [32–34] . The coordination chemistry of neutral triazenes is limited to only a handful of examples, including Pd(II), [35] Ru(II), Os(II) [36] and Ir(I) ( II , Figure 1B).…”

Section: Introductionmentioning

confidence: 99%

Stable CAAC‐Triazenes: A New Nitrogen Ligand System With Donor and Conformational Flexibility, and With Application in Olefin Activation Catalysis

Race,

Hudson,

Albrecht

2024

Chemistry A European J

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N‐heterocyclic imines such as pyridylidene amines impart high catalytic activity when coordinated to a transition metal, largely imposed by their electronic flexibility. Here, this donor flexibility has been applied for the first time to CAAC‐based systems through the synthesis of CAAC‐triazenes. These new ligands offer a larger π‐conjugating that extends from the N‐heterocyclic carbene through three nitrogens rather than just one, as observed in N‐heterocyclic imines. We demonstrate the straightforward synthesis of three new CAAC‐triazenes containing different substituents on the terminal triazene nitrogen. These compounds are remarkably stable up to 120 °C without loss of N2 as typically observed with similar triazenes. E‐to‐Z isomerization within the triazene is instigated by UV light and is partially reversible dependent on the triazene substituent. The quinoline‐substituted CAAC‐triazene 1‐Q has been applied as an L,L’‐type ligand in the synthesis of [PdCl2(1‐Q)], [PdCl(Me)(1‐Q)] and [Pd(Me)(H2O(1‐Q)]+. E‐to‐Z ligand isomerization also occurs when coordinated to PdCl2, providing access to on‐metal manipulation. The cationic complex [PdMe(H2O)(1‐Q)]+ is a precatalyst for oligomerization of ethylene to form initially 2‐butene and subsequently linear and branched C8–C12products from butene activation. Moreover, isomerization of 1‐hexene takes place efficiently with exceptionally low catalyst loading (10 ppm) and up to 74,000 turnover numbers.

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“…2), among which the quite rare azetinyldiazenes (3a, Fig. 2), [35][36][37][38][39] were prepared by standard procedures 40 from the corresponding amines and diazonium salts in good yields. We have chosen different ring sizes from 4 to 7, substituted piperidines and various arenes to investigate scope and limitations.…”

Section: Resultsmentioning

confidence: 99%