Preparation And Light-induced Surface Electron Behavior Of Series Of Transition Metal Coordination Polymers And Supramolecules

With the rapid development of high-technique, material science, biologicalscience and the infiltration of solid physics, the researches about some functionalcomplexes which possess optical, electronic and magnetic specialties have achievedgreat progresses. Electronic behavior has close relations with some functions ofcomplexes. For example, the different distributions, couplings and electron transferscan due to different magnetic properties. The transition of external electron can showdifferent redox specialties and can possess some catalysis effects while the transitionof electron and energy between systems can attribute to some biochemical functions.By this token, the research of external electron behavior has significant meaning forthe functional study of transitional metal complexes. Surface photovoltage spectrumcan supply the information about the surface and interface of solid materials but alsocan study the molecular congeries, electronic states and energy-band structures. It issignificant to study the characteristics and mechanism through surface photovoltagespectrum. The energy gap of some transitional metal complexes is sometimes in theregion of that of semiconductors, therefore we can combine the energy band theorywith the crystal field theory to explain and analyze the response bands. The detectionabout surface charge behavior and photoelectric property of coordinationsupramolecules has the important references and elicitation for exploitingphotoelectric property of transition metal complexes.1. Using normal and solvothermal methods, we have reported twenty-seven Mn, Ni,Cu, Ti polymers and coordination supramolecules. Their structures have beendetermined by using X-ray single crystal diffraction. Their formulas are presented asfollowing:[1] Mn(â…¡/â…£) polymers and coordination supramolecules:(1) [Mn(tpha)(phen)]_n;(2) [Mn(na)₂(H₂O)₂]_n;(3) [Mn(m-tpha)(phen)]_n;(4) {[Mn₃(m-tpha)₂(m-Htpha)₂(bipy)₂]·2H₂O}_n(5) [Mn(2,3-dcp)(H₂O)]_n;(6) [Mn(3,5-dcpyrazole)(H₂O)₂]_n(7) {[Mn(OX)_1.5(H₂O)]·Cl}_n(8) {[Mn(phen)₂(OH)Cl]·Cl·(OH)·(C₉H₁₁NO₂)·2H₂O};(9) [Mn₂(C₈H₇O₂)₄(phen)₂(μ-H₂O)];(10) [Mn₂(btec)(phen)₂(H₂O)₆]·2H₂O;(11) [Mn(phen)₂Cl₂]; (12) [Mn(phen)₂Cl₂]·C₆H₅COOH;(13) [Mn(phen)₂Cl₂](HOC₆H₄CHO)₂·H₂O;(14) [Mn(2,5-dcp)₂(H₂O)₂];(15) [Mn(2,5-dcp)(phen)(H₂O)]·H₂O;(16) [Mn(INA)₂(H₂O)₄];[2] Ni (â…¡) coordination supramolecules:(17) [Ni₃(btc)₂(H₂O)₁₄]·4H₂O(18) [Ni(phen)₂(H₂O)₂]·btc·[Ni(H₂O)₆]_0.5·9H₂O(19) [Ni(3,5-dcpz)₂(H₂O)₂]·H₂O(20) [Ni(2,5-dcp)(H₂O)₄]·2H₂O(21) [Ni(otpha)(Imh)₃(H₂O)₂]·H₂O[3] Cu (â…¡) coordination supramolecules:(22) [Cu₂Cl₄(phen)₂](23) [Cu(C₉H₇NO)₂](24) [Cu(phen)(H₂O)₂·SO₄][4] Ti (â…¢/â…£) polymers:(25)[Ti₂O_0.5(SO₄)_0.5(btec)·H₂SO₄]_n·H₂O(26){[TiO(SO₄)₂]·(C₁₀H₁₀N₂)}_n·2H₂O(27){[Ti1O(SO₄)(HSO₄)][Ti2O(SO₄)(HSO₄)]·(C₁₀H₁₀N₂)}_n·5H₂O2. Beside the structural characterization, the photo-physics property of thesecomplexes has been investigated. The surface photovoltage spectra of the complexesall exhibit positive surface photovoltage responses in 300-800nm, but the intensity,position, number and shape of the responses are different obviously. The distinctionmight be responsible for their structure, species, valence and coordinationenvironment of metal ions in the complexes. From them, we can get some rules asfollowing:[1] The dimension of complexes affects the intensity of the SPS. Moredimensional structure can supply more transmission passages for transferringelectrons or holes, which will improve the intensity of the responses. Generallyspeaking, 3D structure can provide more transmission passages than 2D and 1Dstructure, while 0D structure is bad for transferring electrons or holes. For example,complexes (1)-(3) are Mn(â…¡) polymers which possess 3D, 2D and 1D structurerespectively, the SPV intensity of them weakens gradually.[2] Connected styles of molecules affect the intensity of SPS. The more theinteractions are, the better for the transmission of electron or holes. Coordination bondis beneficial for transferring electrons or holes than hydrogen bond and other weak interactions. When the complexes are all connected to polymer by the same mode, thestronger the interaction, the intensity of the responses will become higher.[3] The kind and valence of the metal ions affect number of the responses.Because the d→d^* transition bands of metal ions are different, the number of theresponses in SPS will show different.[4] The micro-environment of metal ions affects the number and the shape ofresponse bands. When the coordination environment is different, the split of the doribital is also different so the d→d^* transition response bands are distinguished. Forexample, Mn (â…¡) ions can take on different responses when in different field.Meanwhile, if the metal ions have the higher symmetry, the shape of the SPVresponse band is smooth and there seldom appear the splitting peaks.3. We have regards the transitional metal polymers and supramolecules as a kind ofextended semiconductors. We have combined the energy-band theory ofsemiconductors and crystal-field theory of complexes to discuss the SPS of all thecomplexes. Moreover, we have compared the SPV responses with the absorptionbands in UV-Vis spectroscopy which validates the correctness of the assignments inSPS.