Energy-Transfer in CsPbBr_(3)Nanocrystals:Sensitization of Porphyrin Triplets

Sensitizing molecular triplets by colloidal nanocrystals via triplet energy transfer is important for applications such as upconversion or organic synthesis.Typically two step triplet energy transfer(TET)are included in these applications:firstly the triplet energy stored in nanocrystals are extracted into surface ligands,and then the ligands further transfer triplet energy into molecules in bulk solution.Here we report one-step TET application from CsPbBr_(3)perovskite nanocrystals(NCs)to surface-anchored metalloporphyrin derivative molecules(MP).Compared to conventional two-step TET,the one-step TET mechanism possess lower energy loss and higher TET efficiency which is more generally implementable.In this scheme,photoexcitation of CsPbBr_(3)NCs leads to the sensitization of MP ligands triplets which efficiently emit phosphorescence.The enhanced light absorption of MP ligands and down-shifted photon emission can be useful in devices such as luminescent solar concentrators.

Photoisomerization of norbornadiene group in a rigid bichromophoric compound initiated by remote keto chromophore: long-distance through-bond triplet energy transfer

A diad compound 3 beta(bicyclo[2,2,1]hepta-2,5-diene-2-methylcarboxylate-3-carboxy)-androst-5-en-17-one (NBD-S-ONE) was synthesized and its photochemistry was examined. Irradiation of NBD-S-ONE in acetonitrile at lambda > 300 nm selectively excited the keto chromophore. After intersystem crossing, the triplet energy of the keto group was transferred to the NBD group with 18.6% efficiency via a through-bond mechanism, resulting in the isomerization of the latter group to the quadricyclane group.

Theoretical Investigation on Triplet Excitation Energy Transfer in Fluorene Dimer

Triplet-triplet energy transfer in fluorene dimer with electronic structure calculations. The two is investigated by combining rate theories key parameters for the control of energy transfer, electronic coupling and reorganization energy, are calculated based on the diabatic states constructed by the constrained density functional theory. The fluctuation of the electronic coupling is further revealed by molecular dynamics simulation. Succeedingly, the diagonal and off-diagonal fluctuations of the Hamiltonian are mapped from the correlation functions of those parameters, and the rate is then estimated both from the perturbation theory and wavepacket diffusion method. The results manifest that both the static and dynamic fluctuations enhance the rate significantly, but the rate from the dynamic fluctuation is smaller than that from the static fluctuation.

Intramolecular energy transfer between chromophores separated by a rigid steroid bridge——Ⅰ.Singlet and triplet energy transfer in 3β(1-naphthyl)acetoxy-⊿~5-androsten-17-one

Intramolecular transfer of both singlet and triplet electronic excitation between the naphthalene moiety and the carbonyl group in 3β-(1-naphthyl)acetoxy-⊿~5-androsten-17-one was studied.Irradiation with 280 nm light selectively leads to excitation of the naphthalene moiety. Transfer of the singlet excitation from the naphthalene moiety to the carbonyl group occurs by dipole- dipole resonance interaction.The measured rates for such energy transfer in several solvents agree with that calculated from Frster equation.After efficient intersystem crossing,the carbonyl group transfers triplet excitation back to the naphthalene moiety via electron exchange mechanism.The combination of singlet and triplet energy transfer with the high efficiency of intersystcm crossing of carbonyl group results in the phosphorescence enhancement of naphthalene moiety.