Construction Of Phosphine-Protected Coinage-Metal Clusters-Based Materials And Their Applications

During the last decades,the atomically precise coinage-metal(Au,Ag,Cu,etc.)clusters-based materials have attracted significant attention due to their beautiful structures and adjustable photophysical and photochemical properties.Such compounds have shown promising applications in many fields such as biology,medicine,catalysis,optics,and sensing.However,limitations including uncontrollable synthesis and poor stability still hinder their applications.Compared with alkynyl and thiolate ligands,phosphine ligands,which have the stronger coordination ability and controllable spatial configurations,could be used to improve the stability of such clusters,and to broaden their practical applications.In this doctoral thesis,by the functionalization of phosphine ligands and the fine-tuning of metal centers,we successfully prepared a series of fluorescent coinage-metal cluster-based materials.Single crystal X-ray diffraction(SCXRD)and powder X-ray diffraction(PXRD),coupled with density functional theory(DFT)calculations were used to reveal the structure-activity relationship between structure and property.Furthermore,we also explored their potential applications including thermochromism,solvatochromism,bioimaging,ultrafast luminescent detection,and photocatalysis.The main research contents of this dissertation are briefly described as follows.(a)A series of binuclear clusters[Au2(dppaptc)2]Cl2·sol(1·sol,dppaptc=N,N-bis(diphenylphosphanylmethyl)-amino-4-phenyl-thiocarbamide)with variations at Au-S bond lengths were successfully prepared.The introduction of the P-S hybrid ligand dppaptc could generate a suitable coordination environment for Au(I),which could be used to explore the relationship between luminescence and structure.X-ray analysis revealed a linear decrease of Au-S bond lengths combined with a linear correlation with its luminescence intensity at 475 nm,which was confirmed by TD-DFT calculations.Moreover,compound 1,if solvated with H2O and alcohol,possessed the shorter Au-S bonds and enhanced luminescence.The close relationship between luminescence intensity and Au-S length served as a complement to the existing luminescent gold(?)-sulfur systems and provided some new insights into understanding the thermochromism and solvatochromism of the gold(?)-sulfur compounds(b)Based on the results of Chapter 2,we carried out the reactions of[(AuCl)2(bdppmapy)](2)(as a phosphanyl-gold(?)precursor),P-N hybrid ligand N,N-bis(diphenylphosphanyl methyl)-2-aminopyridine(bdppmapy)(as a protecting ligand),and Na2S(as a sulfur source),which gave rise to one tetradecanuclear and one octanuclear Au(?)sulfido clusters,[Au14S6(bdppmapy)5]Cl2(3)and[Au18S8(bdppmapy)6]Cl2(4),respectively.The former displays a new cluster structural framework in the gold cluster chemistry.Compounds 3 and 4 showed strong green luminescence and were employed as excellent imaging probes to selectively light up the lysosome of living cells.Their long-term tracking of lysosomes can be achieved for up to 36 h,while tracking with commercial Lyso-Tracker Red at the same conditions was limited to 3 h.This work demonstrated the new approach for constructing novel gold(?)sulfido clusters supported by special P-N hybrid ligands and the new application of these clusters as long-term selective trackers of lysosomes in bioimaging.(c)This chapter proposed a new guest-lock induced luminescence enhancement mechanism to realize the light-up hypersensitive detection of target VOCs.Through introducing chlorinated hydrocarbons to lock the molecular vibrations within a designed[Cu4I4]-based metal-organic framework(MOF)[Cu4I4(Py3P)2]n(5)(Py3P=tris(2-pyridyl)phosphine),a significant luminescence intensity enhancement can be observed at room temperature,and thus realized the guest-lock induced luminescence enhancement.Weak supramolecular interactions between the host framework and the guest molecules allowed highly sensitive and specific detection of the guest vapor with super-fast response time(<1 s).The single crystal X-ray diffraction(SCXRD)analysis of guest molecules-loaded MOFs and the density functional theory(DFT)calculations were employed to investigate the aforementioned host-guest interactions.Moreover,such a MOF sensor can be used to successfully achieve the ultrafast real-time detection of the toxic chloroaromatic molecule(chlorobenzene).The guest-lock induced light-up mechanism opened up a new route to discover the high-performance hypersensitive light-up luminescent sensors for real-time detection application.(d)Treatment of N,N-bis(diphenylphosphanylmethyl)-3-aminopyridine(3-bdppmapy)with AgX(X=Br,I,CN,SCN,dicyanamide(dca))under different reaction conditions afforded seven complexes including[Ag4I4(3-bdppmapy)2]n(6),[Ag2I2(3?bdppmapy)3]·CH3OH(7·CH3OH),[Ag2Br(3-bdppmapy)3]Br·4CH3OH(8·4CH3OH),[Ag4(CN)4(3-bdppmapy)3]·2CH3OH(9·2CH3OH),[Ag(3-bdppmapy)2]SCN(10),[Ag(3-bdppmapy)2](dca)(11)and {[Ag4(dca)4(3-bdppmapy)2]·4DMF}n(12).Among them,[Ag4I4]-based compound 6 as a representative example exhibited excellent catalytic activity towards the photodecomposition of a spectrum of eleven organic dyes in water under UV light irradiation,and can be reused five times without noticeable decay of its catalytic efficiency.