Excited state properties of an A-D-A non-fullerene electron acceptor: a LC-TD-DFTB study

Understanding charge transfer processes is essential to estimate the performance of organic photovoltaic technologies. Although experimental production is on the rise, predictability strongly relies on theoretical modeling, which is limited to the size of semiconductors. As a computationally favorable approach, we benchmarked the long-range corrected (LC) time-dependent (TD) formulation of the semi-empirical density functional-based tight-binding method (DFTB) for three polycyclic aromatic hydrocarbons (PAHs) and studied the DTP-IC-4Ph molecule, a PAH-based non-fullerene electron acceptor (NFA) with an A-D-A backbone structure. After a thorough investigation into the long-range parameter (ω) tuning for naphthalene, anthracene and pyrene, the excitation energies, oscillator strengths and Natural Transition Orbitals (NTOs) were compared with the standard ωB97X-D/6-31G(d,p) level of theory and the ADC2/6-31G(d,p) multiconfigurational method. We estimated mobility-related properties of the NFA and considered 1000 thermally accessible configurations to qualitatively reproduce the experimental absorption profile and investigate the energetic disorder. Finally, we conducted a fragment-based analysis using the one-electron transition density matrix (1TDM) to determine the character of the excited states and investigate the effect of side chains on exciton formation. Our results are sensitive to the level of theory and highly dependent on the long-range parameter but suggest that the presence of alkyl chains promotes a higher average charge delocalization and allows for additional hopping mechanisms, favoring the charge transfer dynamics.

Tissue Lesions Due to Spirorchiid Eggs in a Loggerhead Turtle ( Caretta caretta Linnaeus 1758) from Brazil: First Report Outside of the United States

Spirorchiids (family Spirorchiidae Stunkard 1921) are a group of flukes that inhabit the circulatory system of turtles. Infection by members of the family Spirorchiidae involves egg deposition in the host bloodstream and accumulation in tissues, which cause inflammatory reactions and embolisms, leading or contributing to the death of the host. Reports of spirorchiid egg lesions in loggerhead turtles ( Caretta caretta Linnaeus, 1758) have only been reported from U.S. hosts. In the present report a female loggerhead sea turtle was found dead on the beach in the north part of the State of Rio de Janeiro, Brazil. During gross necropsy, no parasite egg nodule was found. But the microscopic analysis revealed a mild granulomatous inflammatory process due to eggs from the family Spirorchiidae and both Langhans giant cells and foreign-body giant cells in the heart, kidneys, intestines, lungs, and spleen. The present note is the first record of tissue lesions due to spirorchiid eggs in a loggerhead sea turtle outside the United States.

Spirorchiid Infection in Olive Ridley Turtle, Lepidochelys olivacea (Eschscholtz, 1829) (Testudines: Cheloniidae), from Brazil

The Olive Ridley turtle, Lepidochelys olivacea (Eschscholtz, 1829) (Testudines: Cheloniidae), is 1 of the 5 species of sea turtle found along the coast of Brazil. Little is known regarding infection by species of the family Spirorchiidae in the host, as only 1 report exists. This case report describes granulomas in different tissues associated to type 1 and 3 spirorchiid eggs in 5 L. olivacea from the Brazilian coast. The occurrence of the eggs was considered an incidental finding and may have contributed to the debility and death of the hosts. This is the second report of tissue lesions due to spirorchids eggs in this host and the first occurrence in Olive Ridley turtle from the Brazilian coast.