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De X Zeng

Publications and source records attributed to De X Zeng.

4 recordsLinked to original sources
PubMed2005

Study on photochromism of diarylethenes with a 2,5-dihydropyrrole bridging unit: a convenient preparation of 3,4-diarylpyrroles from 3,4-diaryl-2,5-dihydropyrroles.

Symmetric and nonsymmetric diarylethenes with a 2,5-dihydropyrrole bridging unit have been prepared, and the photochromic properties are investigated. Both symmetric and nonsymmetric diarylethenes with 2,5-dihydropyrrole bridging units undergo reversible ring-opening and ring-closing photoisomerization reactions in nonpolar solvents with UV/vis light, and some of them exhibit good fatigue resistance and no marked degradation detected after 10 cycles via an on/off switch. In polar solvents, however, photochromic diarylethenes with 2,5-dihydropyrrole bridging units produce 3,4-diarylpyrrole derivatives instead of the ring-closing isomer of diarylethenes with UV light irradiation. A class of N-substituted 3,4-diphenylethenes with 2,5-dihydropyrrole bridging units were prepared and used as templates to investigate the conversion reactions. The mechanism of photoconversion of 3,4-diaryl-2,5-dihydropyrroles to 3,4-diarylpyrroles was explored as well.

Journal Article↗
PubMed2004

Study on photochromic diarylethene with phenolic Schiff base: preparation and photochromism of diarylethene with benzoxazole.

A photochromic diarylethene with phenolic Schiff base 1a can be easily transformed to photochromic diarylethene with benzoxazole 3a in the conditions of base and phototrigger. Both of their photochromic properties are investigated. They show that the conversions of ring-open form to ring-closed form at photostationary equilibrium are ca. 20% and 10% for 3a and 1a, respectively, and the backconversions are in nearly quantitative yield for both compounds. They also show that the response time for photostationary equilibrium is ca. 0.5 and 5 min for 3a and 1a, respectively, in the solution. In addition, a general preparation of 2-arylbenzoxazole from phenolic Schiff base in the conditions of base and phototrigger is demonstrated by employing phenolic Schiff bases with different substituted groups as template, and other conditions (solvents, in the presence and absence of oxygen) for preparation of benzoxazole from phenolic Schiff base are explored as well.

Journal Article↗