Iodo-Argentate/-Cuprate(Ⅰ) Hybrids Directed By Supramolecular Structural-Directing Agents: Syntheses And Properties

Structural and functional research of halometallate hybrids have been focus of great interest owing to their structural and chemical diverse,as well as potential application in visible-light sensitizers for photovoltaic cells,switchable nonlinear-optic devices,chromism,field-effect transistors,catalysis,etc.As a branch of the halometallate hybrids,organic templated iodoargentate/cuprate hybrids are especially interesting for their tunable structures and fascinating semiconductor properties,which is mainly dependent on the rational selection of structural directing agents（SDAs）.Although much effort has been paid to various discrete SDAs,and some significant conclusions have been drawn,this field still exist two tough challenges:1)How to realize the controllable structural design of inorganic moieties,such as,dimensionality,symmetry,etc;2)How to assemble novel electron donor-acceptor functional materials based on the electron-rich feature of iodoargentates/cuprates.Herein,different from traditional discrete SDAs,aliphatic or aromatic cations with regular spacer,electron configuration and potential diverse aggregating forms will be used as structural directing agents,to systematically investigate the principle of structural and functional modulation basis on the possible weak interaction modulated structure parameters of the cationic aggregations,flexibility of halometallate framework and their fascinating electronic interactions.Experimental research will be crossly used to evaluate the structural match between structural directing agents and inorganic moieties,and structure-property relationship will be further established.The mian contents and results are as follows:1. Using Dabco molecule with suitable rigidity and two potential N-protonated sites,seven iodoargentate hybrids have been synthesized by simply changing the p H of the reaction solution or benzylation.Interestingly,the hybrids 3–5 display rare halozeotype/chiral structures,and 7 possess the largest halometallate channel with an inner diameter of 1.62 nm so far.Noteworthy,a clear dynamic directing effect can be observed by the different p H-modulated aggregating forms of dabco（hydrogen-bonded dimmer[（Hdabco）（dabco）]⁺（1）,cooperative directing effects as a whole,such as,intrinsic symmetric/chiral correlation,and the regular structure changes of inorganic framework with increasing charge density of dynamic SDCs.Furthermore,the structures of 1-6 and reported protonated dabco and piperazine derivatives of directed iodoargentate hybrids have been summarized and compared,and found that SDA with higher symmetry and lower charge density are more inclined to form highdimensional iodoargentate frameworks.Moreover,1-7 display dimensionality dependent semiconductor,thermal stability and partial photoluminescence properties.This result is important for the elucidation of structural directing rules and provides a potential strategy for the rational construction of novel porous organic-inorganic materials through the flexible modulation of the symmetry and charge density of the dynamic SDCs.2.Directed by in situ protonated or methylated 2/4-Benzylpyridine with potential conformational chirality,six iodoargentate/cuprate hybrids have been synthesized,[（4-Bz-py H）₂（Ag₅Cl₃I₄）]（8）,[（2-Bz-py H）（Ag₅I₆）]·Me CN（9）,[（Me-4-Bz-py）（Ag₄I₅）]（10）,[（4-Bz-py H）₂（Cu₆I₈）]（11）,[（2-Bz-py H）₂（Cu₆I₈）]?H₂O（12）,[（Me-4-Bz-py）₂（Cu₅I₇）]（13）.Clearly,with the changing of N-substitution from proton to methyl,the conformational manifestation of organic molecule change from chiral to achiral at the molecular level,consequential supramolecular aggregating forms and construction of iodoargentate/cuprate frameworks,further amplified and transferred via supramolecular arrangements,exhibiting remarkable hierarchical structural directing ability（acentric 8,9,chiral 11,12 vs central 10,13）.Additionally,iodoargentates possess more flexible adaptability for the information of SDA than iodocuprates.This result indicates the rational selection of conformationally chiral template and versatile weak interactions is an effective strategy for the construction of acentric/chiral organic-inorganic hybrids.3.Using isonicotinamide and its derivative cations as structural directing agents and electron acceptors,seven halometallate hybrids with different compositions and structures have been synthesized,[MCMP][Ag I₂]（14）[MCMP][Ag₃I₄]（15）[HINA][Ag₄I₅]（16）[HINAM]I（17）[HINAM]I·0.5（I₂）（18）[MCMP][Ag₂Br₃]（19）[MCMP][Cu₂I₃]（20）.Interestingly,14-18 exhibit rare electron transfer photochromism based on iodoagentates or iodide ions,which is likely ascribed to the suitable match between weakπ-acids and weak lewis bases,while the disappearance of photochromism in 19 and 20 may result from the unmatched band gaps of two components.Furthermore,the structure,molecular stacking and photochromic performance of 14-18 have been compared and analysed,and found two rules:1）the distance between electron donor and acceptor units is the key factor deciding the photoresponsive range;2)the electron accepting ability of cations,the size of the anions and I…N-C bond angle constitutes the main reason for the photoresponsive time.Noteworthy,although the photochromic behavior can be affected by many factors,the use of dynamic MCMP⁺as structural directing agents and electron acceptors in 14 and 15 reveal unique directing effects and structure-related photochromic properties,especially a fast response rate,a wide response range and a long-lived charge-separated state.To our knowledge,dynamic SDA as electron acceptors has not been used on the modulation of photochromic performance.Obviously,this“dynamic SDA”strategy will provides a new perspective for the development and optimization of electron transfer photochromic hybrids.4.Using N-methyl pyridinium,1,2-bis（pyridinium）methane and 1,4-bis（methylpyridinium）benzene cations as structural directing agents and electron acceptors,three pair isostructural iodoargentate/cuprate hybrids have been synthesized.Noteworthy,23-25 show interesting reversible low temperature thermochromism,and is ascribed to the temperature effects directly on the population of intermolecular CT,while colored compound 22 didn’t show obvious change with the naked eye.Furthermore,the structure,molecular stacking and thermochromic performance have been compared,and found high concentrated charge density on cations,shorter channel distance and perpendicular position between electron donor and acceptor units can not only markedly improve intermolecular charge transfer,but alsodisplaymoreobviousthermochromicbehavior.Thisresultprovides some theories foundation for the optimization and filtering of thermochromic materials.