Photochemistry of insecticide imidacloprid: direct and sensitized photolysis in aqueous medium

The direct and sensitized photodegradations of imidacloprid, 1-(6-chloro-3-pyridinylmethyl)-N-nitro-2-imidazolidinimine, were investigated in aqueous solution and with and without various photo-sensitizers. Results of the study revealed that the intensity of lamp-house and irradiation wavelength had significant effects on the photolysis of imidacloprid. Complete degradation of 20 mg/L imidacloprid in aqueous phase was observed in 40 min under ultraviolet(UV) irradiation system, suggesting the ultraviolet ray played significant role in direct photolysis of imidacloprid. The additions of various photo-sensitizers lead to improve the degradation efficiency of imidacloprid under the irradiation of black light fluorescent lamp. TiO 2 was the most efficient in the photo-catalytic degradation of imidacloprid among other photo-sensitizers in used this study. However, addition of acetone inhibited the photolysis of imidacloprid under the irradiation of UV, indicating the occurrence of competition between acetone and imidacloprid for photos. Mineralization of the imidacloprid was examined to clarify the final photochemical degradation products of the insecticide which were CO 2, Cl- and NO- 3. Complete photo-oxidation of nitrogen to NO- 3 occurred very slowly via the intermediate formation of NH+ 4 and NO- 2.

Synthesis and Photo-acid Generation of a Novel Bis(trichloromethyl)-1,3,5-triazine

A new environmentally friendly photo-acid generator（PAG）, 1-{4＇-[4,6-bis（trichloromethyl）-1,3,5-triazin- 2-yl] [ 1, 1＇-biphenyl]-4-yl}-O-acetyloxime ethanone（TZ4） consisting of both an oxime ester group and a triazine group was designed and synthesized. From the measurements of absorption, fluorescence and the photo-acid generation, it was found that the novel PAG has an excellent radical-generating efficiency. And the other three bis-（trichloromethyl） triazine derivatives 2-[2-（4-methoxyphenyl）ethenyl]-4,6-bis（trichloromethyl）-l,3,5-triazine（TZ1）, 2-[2-（3,4-dimethoxyphenyl）ethenyl]-4,6-bis（trichloromethyl）-1,3,5-triazine（TZ2） and 2-（1,3-benzodioxol-5-yl）-4,6-bis（trichloromethyl）-1,3,5-triazine（TZ3） were synthesized and studied in this work. In the acid measurement, the acid-forming performance of S-triazinyl derivatives was evaluated by the method ascertained in our laboratory. The results indicate that the novel triazine has the better acid-forming performance that subsequently catalyzes the deblocking of a protecting group in copolymers.

Suppression of extension of the photo-sensitive area for a planar-type front-illuminated InGaAs detector by the LBIC technique

To suppress the extension of the photo-sensitive area of a planar-type InGaAs detector, the structure of the detector was modified, and the small-diffusion-area diffusion method, circle-type covering contact and guard-ring were introduced. The laser-beam-induced-current （LBIC） technique was used to study the photo responsive characteristics of the photo-sensitive area of different detector structures. It was indicated that, by modifying the size of the diffusion area, the width of the circle-type covering contact, the distance between the guard-ring and the photo-sensitive area and the working status of the guard-ring, extension of the photo-sensitive area could be effectively suppressed, and the detector photo-sensitive area could be exactly defined.

Photo-promoted transition metal-free organic transformations in the absence of conventional photo-sensitizers

During the last decade,photo-catalysis is emerging as a powerful tool in synthetic organic chemistry.This mini-review summarizes the recent advances of photo-promoted organic transformations under transition metal-free conditions in the absence of conventional photo-sensitizers.