Density Functional Theory Study On The First Hyperpolarizabilities Of Mono-and Bimetal Ir(?)/Rh(?)/Ru(?) Complexes

Nonlinear optical?NLO?materials with good performance are widely used in laser technology,information storage,optical communications and other fields.Therefore,exploring NLO materials with excellent properties has become a hot spot for many scientists.Compared with pure organic NLO materials,organometallic complexes can effectively regulate the second-order NLO response by changing the type,number,oxidation state of the central metal and the change of the ligand.The phenanthroline,bipyridine,pyrrole and other nitrogen heterocyclic complexes have a larger second-order NLO response,due to its strong?electronic delocalization.The second-order NLO response of the molecule can also be effectively regulated by photocyclization,redox.In this paper,the second-order NLO properties of mono-and bimetal Ir?I?/Rh?I?complexes and ruthenium ethynyl complexes were studied by quantum chemistry method.The main results are as follows:?1?The geometry structure,the second-order NLO properties and the electronic spectra of2,2?-bidipyrrins?L?and mono-and bimetal Ir?I?/Rh?I?-L complexes were investigated by density functional theory?DFT?method.The 2,2?-bidipyrrins?L?has a planar configuration,when coordinating with metal,the planar configuration is broken.Compared with the corresponding metal complex,L has obvious unidirectional charge transfer characteristics and hence shows a large first hyperpolarizability value,which is 2.2 to 5.5 times larger than that of others.The first hyperpolarizability of the bimetal Ir/Rh?I?-L complexes were smaller than the corresponding monometallic Ir/Rh?I?-L.This can be attributed to the complex has a multi-directional charge transfer when the complex is formed,and as the number of metals increases,the charge transfer in the opposite direction cancels each other more obviously.The?_vec values for both the mono-and bimetal Rh?I?-L complexes are all larger than the corresponding Ir?I?-L.?2?The second-order NLO properties for a series of half-sandwich ruthenium-based Cp*?dpe?Ru?[Ru*]??Cp*=pentamethylcyclopentadienyl;?dpe?=bis?diphosphine?ethane?metal complexes were investigated by DFT.The calculated results showed that:the system 1,which the[Ru*]acetylide functionality para on the phenylene ring to the dihydroazulene/vinylheptafulvene?DHA/VHF?,have a large?_vec value compared with system2?[Ru*]acetylide meta on the phenylene ring to the DHA/VHF?.It was attributed to the fact that system 1 has the more obvious charge transfer?CT?and the lower transition energy compared with system 2.The system 3 with additional p-phenyl groups had the largest?_vecec value in the studied complexes due to it has the most significant D-?-A intramolecular CT.In addition,the?_vec values of the open-ring complexes were all larger than that of the corresponding closed-ring complexes.In summary,the work provides a theoretical reference for finding the second-order NLO material with excellent performance.