The solutions of rare earth complexes Sm(Phen) 2(TTA)(Bipy)(NO 3) 3 and Sm(L) x (TTA) 4-x (NO 3) 3 [L=Phen (1,10-phenanthroline) or Bipy(2,2′-bipyridine), x =4, 3, 2, 1, 0; TTA is 2-thenoyltrifluoacetone] in EtOH(1&#...The solutions of rare earth complexes Sm(Phen) 2(TTA)(Bipy)(NO 3) 3 and Sm(L) x (TTA) 4-x (NO 3) 3 [L=Phen (1,10-phenanthroline) or Bipy(2,2′-bipyridine), x =4, 3, 2, 1, 0; TTA is 2-thenoyltrifluoacetone] in EtOH(1×10 -3 mol/L) were prepared. The coefficients of antenna effect are 31 5, 18 2 and 5 6 for Phen, Bipy and TTA, respectively, when the electron configuration of the excited state of the samarium atom in the complexes is 4 D 1/2 . The fluorescent intensity and the lifetime of the supramolecular encapsulation products of (CH 3) 3Si-MCM-41 and Sm 3+ complexes are stronger and longer than those of the encapsulation products of MCM-41 and Sm 3+ complexes respectively. The results show that the host with lipophilic channels is more favourable to the fluorescence of the rare earth complexes than the hydrophilic mesoporous molecular sieve. The fluorescent intensity of (CH 3) 3Si-MCM-41-Sm(Phen) 3(TTA)(NO 3) 3 is the strongest \{among\} the encapsulation series of Sm 3+ complexes, which is assumed to result from the greatly reduction of SiO-H vibration relaxation in host (CH 3) 3Si-MCM-41 and the presence of the discrete strong luminescent centres of the guest molecules associated with the nanosized material′s structure. The luminescent decay halftime of the supramolecular materials is much shorter than that of the powder of the samarium complexes. The result shows that the ligand transferring energy from the triplet state to the singlet state of Sm 3+ ( T 1→S , intersystem crossing) becomes higher. The fluorescent experimental results indicate that the interaction between the host and the guest influences the luminescent properties of the nanostructured supramolecular materials.展开更多
Rare earth complexes Eu(Phen)_2(TTA)(Bipy)(NO_3)_3 and Eu(L)_x(TTA)_(4-x)(NO_3)_3 (L=Phen or Bipy; x=4, 3, 2, 1, 0) solutions (1×10^(-3) mol·L^(-1)) were prepared in EtOH. The luminescent experimental result...Rare earth complexes Eu(Phen)_2(TTA)(Bipy)(NO_3)_3 and Eu(L)_x(TTA)_(4-x)(NO_3)_3 (L=Phen or Bipy; x=4, 3, 2, 1, 0) solutions (1×10^(-3) mol·L^(-1)) were prepared in EtOH. The luminescent experimental results show that the synergy effect of Phen and TTA exists in Eu^(3+) complexes. But when the ligands of Bipy and TTA coexist in europium complex, the synergy effect does not exist. If a solution of a europium complex has a specific electron configuration of excited state, the solution of the complex has an intensity of fluorescence and a quantum yield. 2.5×10^(-5) mol·L^(-1) Eu(Phen)_2(TTA)_2(NO_3)_3 solution (λ_(ex)=347.0 nm) possesses a maximal quantum yield (0.25) and the strongest fluorescent intensity. The nanosized mesoporous molecular sieves possess spherical cage structure that is fit for preparation of composite materials with encapsulation method. The research results of XRD and IR show that the guest molecule is encapsulated into the channels of the host. The thermostability of the guest molecule in the channels of the host (CH_3)_3Si-MCM-41 is enhanced. The fluorescent intensity and the half-life of nanosized composites of (CH_3)_3Si-MCM-41 and Eu^(3+) complexes are stronger and longer than those of encapsulation products of MCM-41 and Eu^(3+) complexes. Supramolecular encapsulation products emit characteristic radiation of Eu^(3+) ion, vesting in the transitions of (()~5D_0→()~7F_J) (J=0, 1, 2, 3, 4), respectively; each excitation peak of fluorescent spectra of the composites is assigned to an excited electron configuration of Eu^(3+) ion. The host with lipophilic channels is more favourable to fluorescence of the rare earth complex than hydrophilic mesoporous molecular sieve; The fluorescent intensity of (CH_3)_3Si-MCM-41-Eu(Phen)(TTA)_3(NO_3)_3 can match with that of Eu(Phen)(TTA)_3(NO_3)_3 powder sample. These results could be assumed to result from strong radiation absorption of the guest complex molecule (blue shift of maximum excitation wavelength), greatly reducing of silanol group vibration relaxation of the host (CH_3)_3Si-MCM-41, energy transfer from host to guest, and presence of discrete luminescent center associated with nanosized material structures. The selectivity of host to guest and the interaction between the host and the guest influence greatly the luminescent properties of supramolecular system.展开更多
Among rare earth complexes Tb(Phen)_ x (Bipy)_((4- x ))(NO_3)_3 ( x =4,3,2,1,0) solutions (1×10 (-3) (mol·L (-1)),) the fluorescent intensity of Tb (3+) in Tb(Phen)_3(Bipy)(NO_3)_3 is strongest and that of T...Among rare earth complexes Tb(Phen)_ x (Bipy)_((4- x ))(NO_3)_3 ( x =4,3,2,1,0) solutions (1×10 (-3) (mol·L (-1)),) the fluorescent intensity of Tb (3+) in Tb(Phen)_3(Bipy)(NO_3)_3 is strongest and that of Tb (3+) in Tb(Bipy)_4(NO_3)_3 is weakest. The fluorescent intensity of Tb (3+) in (CH_3)_3Si-MCM-41-Tb(Bipy)_4(NO_3)_3 is strongest and that of Tb (3+) in MCM-41-Tb(Phen)_3(Bipy)(NO_3)_3 or (CH_3)_3Si-MCM-41-Tb(Phen)_3(Bipy)(NO_3)_3 becomes very weak. Luminescence supramolecular nanostructured materials that the guests Tb(Phen)_4(NO_3)_3 and Tb(Bipy)_4(NO_3)_3 were encapsulated in the non-polar channels of (CH_3)_3Si-MCM-41 are stronger than that encapsulated in the polar channels of MCM-41. When the guests are Tb(Phen)_3(Bipy)(NO_3)_3 and Tb(Phen)_2(Bipy)_2(NO_3)_3,the result is just opposite. The results were proved by fluorescent lifetime experiments. MCM-41-Tb(Phen)(Bipy)_3(NO_3)_3 shows two distinct exponential decays,which time constants are 168.8 and 641.1 μs and its amplitude ratio is 0.96∶1. The same as (CH_3)_3Si-MCM-41-Tb(Phen)(Bipy)_3(NO_3)_3 shows,of which are 73.2 and 590.4 μs and the amplitude ratio is 2.3∶1. The ratios of decay time and luminescence intensity of the both supramolecular systems are 2.5∶1,1∶2.5 and 1.1∶1,0.96∶1,respectively. These results indicate that interaction and selectivity between host and guest influence greatly luminescent properties of supramolecular system.展开更多
基金Supported by the Science Foundation of Guangzhou City( 2 0 0 0 - Z- 0 76 - 0 1),L aboratory of Rare Earth Chemistry andPhysics,Changchun Institution of Applied Chemistry,Chinese Academ y of Sciences and Key L aboratory of Inorganic Synthe-sis and Pr
文摘The solutions of rare earth complexes Sm(Phen) 2(TTA)(Bipy)(NO 3) 3 and Sm(L) x (TTA) 4-x (NO 3) 3 [L=Phen (1,10-phenanthroline) or Bipy(2,2′-bipyridine), x =4, 3, 2, 1, 0; TTA is 2-thenoyltrifluoacetone] in EtOH(1×10 -3 mol/L) were prepared. The coefficients of antenna effect are 31 5, 18 2 and 5 6 for Phen, Bipy and TTA, respectively, when the electron configuration of the excited state of the samarium atom in the complexes is 4 D 1/2 . The fluorescent intensity and the lifetime of the supramolecular encapsulation products of (CH 3) 3Si-MCM-41 and Sm 3+ complexes are stronger and longer than those of the encapsulation products of MCM-41 and Sm 3+ complexes respectively. The results show that the host with lipophilic channels is more favourable to the fluorescence of the rare earth complexes than the hydrophilic mesoporous molecular sieve. The fluorescent intensity of (CH 3) 3Si-MCM-41-Sm(Phen) 3(TTA)(NO 3) 3 is the strongest \{among\} the encapsulation series of Sm 3+ complexes, which is assumed to result from the greatly reduction of SiO-H vibration relaxation in host (CH 3) 3Si-MCM-41 and the presence of the discrete strong luminescent centres of the guest molecules associated with the nanosized material′s structure. The luminescent decay halftime of the supramolecular materials is much shorter than that of the powder of the samarium complexes. The result shows that the ligand transferring energy from the triplet state to the singlet state of Sm 3+ ( T 1→S , intersystem crossing) becomes higher. The fluorescent experimental results indicate that the interaction between the host and the guest influences the luminescent properties of the nanostructured supramolecular materials.
文摘Rare earth complexes Eu(Phen)_2(TTA)(Bipy)(NO_3)_3 and Eu(L)_x(TTA)_(4-x)(NO_3)_3 (L=Phen or Bipy; x=4, 3, 2, 1, 0) solutions (1×10^(-3) mol·L^(-1)) were prepared in EtOH. The luminescent experimental results show that the synergy effect of Phen and TTA exists in Eu^(3+) complexes. But when the ligands of Bipy and TTA coexist in europium complex, the synergy effect does not exist. If a solution of a europium complex has a specific electron configuration of excited state, the solution of the complex has an intensity of fluorescence and a quantum yield. 2.5×10^(-5) mol·L^(-1) Eu(Phen)_2(TTA)_2(NO_3)_3 solution (λ_(ex)=347.0 nm) possesses a maximal quantum yield (0.25) and the strongest fluorescent intensity. The nanosized mesoporous molecular sieves possess spherical cage structure that is fit for preparation of composite materials with encapsulation method. The research results of XRD and IR show that the guest molecule is encapsulated into the channels of the host. The thermostability of the guest molecule in the channels of the host (CH_3)_3Si-MCM-41 is enhanced. The fluorescent intensity and the half-life of nanosized composites of (CH_3)_3Si-MCM-41 and Eu^(3+) complexes are stronger and longer than those of encapsulation products of MCM-41 and Eu^(3+) complexes. Supramolecular encapsulation products emit characteristic radiation of Eu^(3+) ion, vesting in the transitions of (()~5D_0→()~7F_J) (J=0, 1, 2, 3, 4), respectively; each excitation peak of fluorescent spectra of the composites is assigned to an excited electron configuration of Eu^(3+) ion. The host with lipophilic channels is more favourable to fluorescence of the rare earth complex than hydrophilic mesoporous molecular sieve; The fluorescent intensity of (CH_3)_3Si-MCM-41-Eu(Phen)(TTA)_3(NO_3)_3 can match with that of Eu(Phen)(TTA)_3(NO_3)_3 powder sample. These results could be assumed to result from strong radiation absorption of the guest complex molecule (blue shift of maximum excitation wavelength), greatly reducing of silanol group vibration relaxation of the host (CH_3)_3Si-MCM-41, energy transfer from host to guest, and presence of discrete luminescent center associated with nanosized material structures. The selectivity of host to guest and the interaction between the host and the guest influence greatly the luminescent properties of supramolecular system.
文摘Among rare earth complexes Tb(Phen)_ x (Bipy)_((4- x ))(NO_3)_3 ( x =4,3,2,1,0) solutions (1×10 (-3) (mol·L (-1)),) the fluorescent intensity of Tb (3+) in Tb(Phen)_3(Bipy)(NO_3)_3 is strongest and that of Tb (3+) in Tb(Bipy)_4(NO_3)_3 is weakest. The fluorescent intensity of Tb (3+) in (CH_3)_3Si-MCM-41-Tb(Bipy)_4(NO_3)_3 is strongest and that of Tb (3+) in MCM-41-Tb(Phen)_3(Bipy)(NO_3)_3 or (CH_3)_3Si-MCM-41-Tb(Phen)_3(Bipy)(NO_3)_3 becomes very weak. Luminescence supramolecular nanostructured materials that the guests Tb(Phen)_4(NO_3)_3 and Tb(Bipy)_4(NO_3)_3 were encapsulated in the non-polar channels of (CH_3)_3Si-MCM-41 are stronger than that encapsulated in the polar channels of MCM-41. When the guests are Tb(Phen)_3(Bipy)(NO_3)_3 and Tb(Phen)_2(Bipy)_2(NO_3)_3,the result is just opposite. The results were proved by fluorescent lifetime experiments. MCM-41-Tb(Phen)(Bipy)_3(NO_3)_3 shows two distinct exponential decays,which time constants are 168.8 and 641.1 μs and its amplitude ratio is 0.96∶1. The same as (CH_3)_3Si-MCM-41-Tb(Phen)(Bipy)_3(NO_3)_3 shows,of which are 73.2 and 590.4 μs and the amplitude ratio is 2.3∶1. The ratios of decay time and luminescence intensity of the both supramolecular systems are 2.5∶1,1∶2.5 and 1.1∶1,0.96∶1,respectively. These results indicate that interaction and selectivity between host and guest influence greatly luminescent properties of supramolecular system.
