Synthesis And Photophysical Property Of Broadband Visible Light Harvesting N^N Pt(?) Bisacetylide Complex

Transition metal complexes can apply in several areas,such as photovoltaics,photocatalytic H2 production,photo oxidation reduction,photoinitiated polymerization,photodynamic therapy,and the triplet-triplet annihilation(TTA)upconversion as they showing visible light absorption and long-lived triplet excited state.One of the challenges for transition metal complexes is the limited absorption in visible spectral range.When the complex have broadband absorption,it can harvest most of the energy from a broadband light source.However,most transition metal complexes only have a single light-harvesting chromophore,thus there is only one major absorption band in visible range.To this end,we prepared two broadband visible light harvesting N^N Pt(?)bisacetylide complexes and studied their photophysical property.1.A N^N Pt(?)complex,Pt-1,with two heteroleptic ligands was prepared.We choose two different acetylide ligands,i.e.,boron-dipyyromethane(BDP)and naphthalenediimide(NDI)chromophores,which show strong and braodband absorption in visible region.The platinum complex shows broadband visible light absorption(400 nm-620 nm),molar extinction coefficient is up to 97000 M-1cm-1.This unique structural protocol ensure the competing intersystem crossing(ISC)and resonance energy transfer(FRET)in the complex,FRET and ISC time costants are 8.6 ps(k FRET = 1.2 × 1011 s-1)and 308 ps(k ISC = 3.2 × 109s-1).The complex's triplet state is localized on NDI moiety,and the triplet state lifetime is28.1 ms.Besides,the two-color excitable triplet-triplet annihilation upconversion using the Pt(?)complex as triplet photosensitizer was studied as well,perylene was used as acceptor,the upconversion quantum yield was determined as 4.1 % and 1.4 %.2.We synthetized a N^N Pt(?)bisacetylide complex with perylenemonoimide(PMI)ligand(Pt-PMI).The complex shows broadband visible light absorption(420 nm-620 nm),molar extinction coefficient is up to 67000 M-1cm-1.Nanosecond and DFT calculation show the triplet state is localized on PMI moiety,and the triplet state lifetime is 7.6 ms.We choose perylenebisimide(PBI)as acceptor to do TTA upconversion experiment,the upconversion quantum yield of the Pt(?)complex is 3.5 %.