Table of Content

23 March 2002, Volume 20 Issue 2

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HULA-TWIST IN PHOTOISOMERIZATION: ORGANIC SYSTEMS

Robert S.H.LIU

2002, 20(2):  81-87.  DOI: 10.7517/j.issn.1674-0475.2002.02.81

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Literature examples of photoisomerization involving organic compounds under confined conditions are summarized.They are shown to be consistent with the Hula twist mechanism of isomerization.Thus,the results support the theory that such a volume conserving reaction mechanism is favored for photoreactions of substrates under conditions where the medium plays a significant role,i.e.,a supramoleclar process.

SYNTHESIS AND PHOTOSENSITIVITY OF NOVEL PHOTOSENSITIVE EPOXY POLYSILOXANE OLIGOMER

HUANG Yu-li, LIU Ji, WANG Tao, LIU Hua-feng

2002, 20(2):  88-95.  DOI: 10.7517/j.issn.1674-0475.2002.02.88

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A photosensitive oligomer,cycloaliphatic epoxy polysiloxane,and a new kind of cationic photoinitiator,[CpFe(η 6 tol)]BF 4,was synthesized.The influences of photoinitiators,ratio of oligomer to monomer,and promoters on the rate of photoinitiated cationic polymerization of cycloaliphatic epoxy polysiloxane systems were studied.It shows that the polysiloxane is a high photosensitive oligomer,with a 165 mL/cm 2 optimized photosensitivity when initiated by diaryliodonium salt SR 1012 with sensitizer 651. Moreover,the ability of dark cure of the polysiloxane when initiated by [CpFe(η 6 tol)] BF 4was discussed.

SYNTHESIS OF VANADYL PHTHALOCYANINE AND STUDY ON STRUCTURES AND PHOTOVOLTAIC PROPERTIES OF ITS FILMS

ZHANG Qing, HUANG DE yin, LIU Yan-gang, XUE Min-zhao, CHEN Ling-bing

2002, 20(2):  96-99.  DOI: 10.7517/j.issn.1674-0475.2002.02.96

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The transient photovoltaic response of the Al\phase Ⅱ VOPc\ITO sandwich cell excited by pulse laser beam of 355 nm,532 nm,1 064 nm wavelength at different intensities were investigated in this paper.It has been found that the magnitude of the transient photovoltaic peaks of the cell increased with increasing the intensity of the incident light.Both under illumination of 532 nm pulse laser and 1 064 nm pulse laser,the cell gave only negative photovoltaic signal with no relations to the direction of the incident light.On the contrary,under illumination of 355 nm pulse laser,the polarity of the photovoltaic response depended on the direction of the incident light.It was negative when the VOPc film was illuminated through aluminum eletrode,while positive when the VOPc film was illuminated through ITO eletrode.This confirmed our conclusion from the investigation on steady state cw(continious wavelength)photovoltage response of the cells in the former paper,that there were two different mechanisms for the photovoltaic response of Al\phase Ⅱ VOPc\ITO sandwich cell.

ANODIC INHIBITION OF 1-PHENYL-5-MERCAPTOTETRAZOLE AND BENZOTRIAZOLE ON COLLOIDAL PARTICLES OF SILVER AND SILVER SULPHIDE

SHI Yao, YAO Lin-hui, ZHAO Wen-fang, XIA Pei-jie

2002, 20(2):  100-110.  DOI: 10.7517/j.issn.1674-0475.2002.02.100

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In order to investigate the different effects of inhibitors on colloidal particles of silver and silver sulphide,the anodic inhibitions of 1-pheny-l5-mercaptotetrazole (PMT) and benzotriazole (BTA) were examined by physical development catalyzed with Ag and Ag₂S particles.The results are shown as follows: 1)that both PMT and BTA gave rise to inhibitions, to some extent,on Ag particles and Ag₂S(Ag) particles prepared under slight excess of silver ions,but did not give inhibitions to Ag₂S(S) particles prepared in slight excess of sulfur ions because adsorption of the excessive sulfur ions on Ag₂S particles was stronger than that of these inhibitors;2)that in the presence of S₂O₃^2- and I^- ions,the inhibition of BTA on Ag was not only eliminated,but the activity of Ag particles in catalyzing the physical development was even higher than that of Ag without addition of BTA,however,S₂O₃^2- and I^- ions gave no effects on the inhibition of Ag₂S particles with BTA;3)that in the case of PMT,S₂O₃^2- and I^- ions were not able to eliminate the intibition of PMT on Ag particles,but slightly increased or decreased the inhibitions on Ag₂S(Ag) or Ag₂S(S),respectively;4)that the measurements of SERS(Surface Enhancement of Raman Spectrometry)confirmed that the inhibition of BTA on Ag particles resulted from the adsorption and disappearance of an inhibition of BTA in the presence of S₂O₃^2- and I^- ions resulted from the desoption of BTA on Ag particles.All this means the importance of the anodic mechanism for inhibition.

NEW OBSERVATION OF CYCLIC VOLTAMMETRIC BEHAVIOR OF Ag⁺-ZEOLITE MODIFIED ELECTRODE

LI Yong-jun, LIU Chun-yan

2002, 20(2):  111-117.  DOI: 10.7517/j.issn.1674-0475.2002.02.111

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The cyclic voltammegrams(CV)of silver ions exchanged zeolite modified electrode(Ag⁺-zeolite)differed from the behavior of silver ions from an aqueous solution on solid sliver electrode.The formation of silver clusters in the pores of zeolite had a significant effect on the CV behavior of electrodes.In light of CV characteristics of Ag⁺-zeolite electrodes in the electrolyte solution containing anions forming insoluble salt with Ag⁺-,a selectivity of Ag⁺-zeolite for anions was proposed to explain CV characteristics of Ag⁺-zeolite Y.

A STUDY ON THE DEVICE PROBLEM OF CATIONIC FLUORESCENCE SENSOR

WANG Hui, MEI Ming-hua, FANG Yu, ZHANG Xiao-hong, WU Shi-kang

2002, 20(2):  118-125.  DOI: 10.7517/j.issn.1674-0475.2002.02.118

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The device of an ultra thin film fluorescence sensor with polyamino chain naphthyl group modified onto a quartz plate surface has been prepared.The fluorescence quenching of the sensor by different metallic cations was studied in both aqueous and organic solvents.It was found that in the fluorescence spectrum of device either in aqueous or in organic solvents there were both monomer and excimer emission peaks.When it was dipped in the aqueous solution of nickel cation,the intensity of the monomer peak increased in the region of low concentration of nickel cation added,then,decreased in the region of high concentration.However,the intensity of excimer emission just decreased with the change of cationic concentration.In the copper ionic aqueous solution,the tendency of fluorescence changing of device was different to that of nickel ion.Only a decreasing tendency was observed for the monomer peak emission while the copper ion concentration increased.And for the excimer emission there was no big change observed.The fluorescence quenching of molecule of studied sensor dissolved in organic solvent was different with that when it was attached on the surface of device.It indicated that the configuration and the structure of molecule attached on the surface of device compared with the molecule in solution were different evidently.

STUDIES ON THE LIFETIME OF M-STATE IN BACTERIORHODOPSIN FILM MODIFIED WITH CeO₂ NANOCRYSTALLINE

WANG Li-ping, LI Bao-fang, HONG Guang-yan, JIANG Long

2002, 20(2):  126-130.  DOI: 10.7517/j.issn.1674-0475.2002.02.126

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Bacteriorhodopsin,which consisted in the purple membrane,has unique photocycle and photochoromism properties and can be widely used in moleculer electronics and bioelectrotechnics.Bacteriorhodopsin polyvinyl alcohol (bR-PVA)films were prepared with CeO₂ nanocrystallines as chemical additives.The effect of the nanocrystallines on the lifetime of M-state,which is an important intermediate in the photocycle of bR,is investigated.It is observed that the lifetime of M-state can be prolonged by rare-earth nanocrystalline,and the lifetime of M-state increases with the decreasing size of CeO₂ nanocrystalline.Hydroxyl groups around the nanocrystallines help to prevent the Schiff base in the M-state from uptaking protons,and the decay rate is retarded and the lifetime of the M intermediate is prolonged.

DEVELOPMENT OF SECOND GENERATIONAL PORPHYRIN-BASED PHOTOSENSITIZERS

MA Jin-shi

2002, 20(2):  131-148.  DOI: 10.7517/j.issn.1674-0475.2002.02.131

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The current state of seond generational prophyrin based photosensitizers used in photodynamic therapy (PDT) is reviewed,which are most chlorins in the stages of clinical and pre-clinical trials.The research on photophysical properties showed that they are powerful photodynamic drugs.Some biological molecule linked porphyrins and boronated derivatives are also presented,which may have good future used for phototherapeutic agents.

RESEARCH PROGRESS OF LOW MOLECULAR WEIGHT COMPLEX ELECTROLUMINESCENT MATERIALS

JIANG Hua, LIU Yun-qi, WU Xia, ZHANG Yong-an, JIN Lin-pei

2002, 20(2):  149-158.  DOI: 10.7517/j.issn.1674-0475.2002.02.149

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The basic principles of organic electroluminescence and organic light emitting diodes are presented.The recent progress of low molecular weight complex electroluminescent materials in summarized.Their photoelectronic properties,luminescent efficiency and stability of the electroluminescent devices are discussed.