Synthesis And Characterization Of Photochromic Hybrids With Dimethylbenzotriazolium Iodometallates

Photochromic organic-inorganic hybrid materials,especially based on electron transfer,have attracted intense interest owing to their important actual or potential application value in optical information storage,optical sensors,optical power limiting switch,energy conversion and other fields.However,electron acceptors are mainly concentrated on the strong accepting capability of viologens,1,4,5,8-Naphthalenediimides(NDIs),which are usually matched with strong Lewis bases as donors,such as chlorometallates,carboxylates,zoelites,and phosphates.In this thesis,using in situ methylated benzotriazolium as structural directing agent and moderate electron acceptor,seven iodometallate hybrids with different anion frameworks and photochromic properties have been synthesized by modulation of supramolecular aggregation of DMBTz~+.On the basis of structural analysis,their photochromic mechanism and structure-property relationship were investigated by electron paramagnetic resonance,powder diffraction,UV-Vis diffuse reflectance spectroscopy and thermogravimetric analysis differential scanning calorimetry.Preliminary results are listed as follow:1?Structural directing abilities of DMBTz~+ cations: DMBTz~+ cations as structure directing agents possess a strong and versatile polymeric tendency via weak p-p interactions,corresponding to the dimension of iodoargentates,which exhibit dynamic structure-directing effect of DMBTz~+ cations and flexibility of iodoargentate frameworks.2?The rule of photochromism: I/DMBTz~+ ratio is the decisive factor for photochromism and the degree of coloration of dimethylbenzotriazolium iodoargentate system,while the N···I distance is the main factor to determine the optical response rate.The moderate electron accepting ability of DMBTz~+ cation matched with relatively weak donating ability of metal iodine,is tendency to form weak CT complex,which is beneficial for the net photoindced electron transfer as well as the improvement of photochromic properties.The unmatch of the energy levels of donor and acceptor may be the main reason for the absence of photochromic properties of dimethylbenzotriazolium iodocuprate hybirds.