Integrating multiple photosensitive properties into an“all-in-one”photosensitizer(PS)shows great promise for the treatment of cancers owing to synergistic effect among them.However,the development of such PSs,especi...Integrating multiple photosensitive properties into an“all-in-one”photosensitizer(PS)shows great promise for the treatment of cancers owing to synergistic effect among them.However,the development of such PSs,especially those that need a single laser source,remains a challenge.Herein,we report an orchestration of electron donors and acceptors in a propeller-like pentad,PBI-4Cz,where four carbazole(Cz)units are covalently linked to the ortho-positions of the perylene bisimide(PBI)core.Strong intramolecular donor-acceptor interaction significantly quenches the luminescence and largely extends the absorption spectra to near-infrared region.Excited-state dynamics investigated via femto-and nano-second transient absorption spectroscopy revealed exclusive charge separation of the PBI-4Cz within initial 0.5 ps when photoexcited regardless of which intermediate is involved.Energy dissipation of the resulting charge-separated state(PBI^(•−)-4Cz^(•−))is subjected to the toggle between intersystem-crossing toward excited triplet states and charge recombination toward ground states.Relative importance of the two pathways can be tuned by micro-environmental polarity,which endows PBI-4Cz remarkable performances of singlet-oxygen generation(>90.0%)in toluene and photothermal conversion(∼28.6%)in DMSO.Harnessing intrinsic photostability and excited-state processes of heavy-atom-free PBI derivatives not only holds a promise for multifunctional phototheranostics,but also provides a prototype for designing high-performance PSs with tunable photoconversion pathways.展开更多
We have fabricated a new perylene bisimide(PBI)folda-dimer(BPBI-CB-1)by tethering two PBI moieties to the ortho-carbon positions of a carborane unit.The synthesized compound adopted distinct configurations in differen...We have fabricated a new perylene bisimide(PBI)folda-dimer(BPBI-CB-1)by tethering two PBI moieties to the ortho-carbon positions of a carborane unit.The synthesized compound adopted distinct configurations in different solvents with dual emissions as its characteristic.The two PBI moieties in the molecule appeared either in a weakly interacted,monomer-like state or brought into close π-π contact with each other,forming an interacted stacking state.The equilibrium between these two states was governed by the nature of solvents and testing temperature.Spectroscopic and theoretical studies concluded that dual emission bands originated from intramolecular monomer-like and stacking states,respectively.Remarkably,in a solvent like 1,2-dichloroethane(DCE),both emission intensities increased with rising temperatures.The positive temperature response of the monomer emission was ascribed to an increased amount of monomer-like population,owing to its endothermic energy state,while the excimer emission was rationalized by increased population of the bright exciton state,resulting in an increased emission yield that compensated the diminished population of the stacking state.To our knowledge,this is the first report on positive temperature-responsive dual emissions associated with the synergism of intramolecular intersubunit aggregation/dissociation and excimer transformation.展开更多
基金supported by the Natural Science Foundation of China(21820102005,22132002)111 project(B14041)+1 种基金the Fundamental Research Funds for the Central Universities of China(2019TS033,GK202001005 and GK202003034)the Youth Innovation Team of Shaanxi Universities。
文摘Integrating multiple photosensitive properties into an“all-in-one”photosensitizer(PS)shows great promise for the treatment of cancers owing to synergistic effect among them.However,the development of such PSs,especially those that need a single laser source,remains a challenge.Herein,we report an orchestration of electron donors and acceptors in a propeller-like pentad,PBI-4Cz,where four carbazole(Cz)units are covalently linked to the ortho-positions of the perylene bisimide(PBI)core.Strong intramolecular donor-acceptor interaction significantly quenches the luminescence and largely extends the absorption spectra to near-infrared region.Excited-state dynamics investigated via femto-and nano-second transient absorption spectroscopy revealed exclusive charge separation of the PBI-4Cz within initial 0.5 ps when photoexcited regardless of which intermediate is involved.Energy dissipation of the resulting charge-separated state(PBI^(•−)-4Cz^(•−))is subjected to the toggle between intersystem-crossing toward excited triplet states and charge recombination toward ground states.Relative importance of the two pathways can be tuned by micro-environmental polarity,which endows PBI-4Cz remarkable performances of singlet-oxygen generation(>90.0%)in toluene and photothermal conversion(∼28.6%)in DMSO.Harnessing intrinsic photostability and excited-state processes of heavy-atom-free PBI derivatives not only holds a promise for multifunctional phototheranostics,but also provides a prototype for designing high-performance PSs with tunable photoconversion pathways.
基金the Natural Science Foundation of China(nos.21820102005,21527802,and 21673133)China 111 project(no.B14041)Program for Changjiang Scholars and Innovative Research Team in University(no.IRT-14R33).
文摘We have fabricated a new perylene bisimide(PBI)folda-dimer(BPBI-CB-1)by tethering two PBI moieties to the ortho-carbon positions of a carborane unit.The synthesized compound adopted distinct configurations in different solvents with dual emissions as its characteristic.The two PBI moieties in the molecule appeared either in a weakly interacted,monomer-like state or brought into close π-π contact with each other,forming an interacted stacking state.The equilibrium between these two states was governed by the nature of solvents and testing temperature.Spectroscopic and theoretical studies concluded that dual emission bands originated from intramolecular monomer-like and stacking states,respectively.Remarkably,in a solvent like 1,2-dichloroethane(DCE),both emission intensities increased with rising temperatures.The positive temperature response of the monomer emission was ascribed to an increased amount of monomer-like population,owing to its endothermic energy state,while the excimer emission was rationalized by increased population of the bright exciton state,resulting in an increased emission yield that compensated the diminished population of the stacking state.To our knowledge,this is the first report on positive temperature-responsive dual emissions associated with the synergism of intramolecular intersubunit aggregation/dissociation and excimer transformation.
