TY - JOUR
T1 - Characterization of Charge Transfer in Excited States of Extended Clusters of π-Stacked Donor and Acceptor Complexes in Lock-Arm Supramolecular Ordering
AU - Chen, Rui Xue
AU - Aquino, Adélia J.A.
AU - Sue, Andrew C.H.
AU - Niehaus, Thomas
AU - Lischka, Hans
N1 - Publisher Copyright:
© 2019 American Chemical Society.
PY - 2019/5/30
Y1 - 2019/5/30
N2 - Lock-arm supramolecular ordering cocrystals formed by π-stacked materials constitute an interesting class of materials, which exhibits ferroelectric behavior at room temperature. To characterize the charge transfer in excited states, two complexes with π-stacked donors and acceptors, the 1,5-naphthalene diol (NDI) donor and pyromellitic diimide with diethylene glycol arms (PDIA) acceptor, 5-amino-1-naphthol (AMN) donor and PDIA acceptor, were investigated. The electronic excitations were calculated using the scaled opposite-spin variant of ADC(2), time-dependent density functional theory (TD-DFT) using a long-range corrected (LC) functional (ωB97xD), and the TD-LC approach within density-functional-based tight binding (TD-LC-DFTB). Face-to-face mixed stacks and edge-to-face crossed stacks up to hexamers were investigated. The calculations show that the ground state of the complexes does not possess significant CT character. On the other hand, the lowest excited state (S1) shows in all clusters a strong charge transfer. In several cases, the second excited state and also higher excited singlet states possess significant CT character. The orbitals involved in the excitation are mostly well localized and located on adjacent donor/acceptor pairs. Comparing different stacking directions, the vertical excitation energies for the NDI-PDIA crossed stacks are larger than those for the mixed stacks by 0.2-0.4 eV. In the case of the AMN-PDIA system, the energy differences are smaller (∼0.1 eV) with mostly the same energetic ordering as for the NDI-PDIA case. Strong red shifts in vertical fluorescence emission transitions have been computed, which could even lead to intersection between ground and first excited states, resulting in ultrafast radiationless decay and fluorescence quenching.
AB - Lock-arm supramolecular ordering cocrystals formed by π-stacked materials constitute an interesting class of materials, which exhibits ferroelectric behavior at room temperature. To characterize the charge transfer in excited states, two complexes with π-stacked donors and acceptors, the 1,5-naphthalene diol (NDI) donor and pyromellitic diimide with diethylene glycol arms (PDIA) acceptor, 5-amino-1-naphthol (AMN) donor and PDIA acceptor, were investigated. The electronic excitations were calculated using the scaled opposite-spin variant of ADC(2), time-dependent density functional theory (TD-DFT) using a long-range corrected (LC) functional (ωB97xD), and the TD-LC approach within density-functional-based tight binding (TD-LC-DFTB). Face-to-face mixed stacks and edge-to-face crossed stacks up to hexamers were investigated. The calculations show that the ground state of the complexes does not possess significant CT character. On the other hand, the lowest excited state (S1) shows in all clusters a strong charge transfer. In several cases, the second excited state and also higher excited singlet states possess significant CT character. The orbitals involved in the excitation are mostly well localized and located on adjacent donor/acceptor pairs. Comparing different stacking directions, the vertical excitation energies for the NDI-PDIA crossed stacks are larger than those for the mixed stacks by 0.2-0.4 eV. In the case of the AMN-PDIA system, the energy differences are smaller (∼0.1 eV) with mostly the same energetic ordering as for the NDI-PDIA case. Strong red shifts in vertical fluorescence emission transitions have been computed, which could even lead to intersection between ground and first excited states, resulting in ultrafast radiationless decay and fluorescence quenching.
UR - http://www.scopus.com/inward/record.url?scp=85066140971&partnerID=8YFLogxK
U2 - 10.1021/acs.jpca.9b02208
DO - 10.1021/acs.jpca.9b02208
M3 - Article
C2 - 31050426
AN - SCOPUS:85066140971
SN - 1089-5639
VL - 123
SP - 4532
EP - 4542
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 21
ER -