Recent progress in heavy atom-free organic compounds showing unexpected intersystem crossing (ISC) ability

Abstract

In this review, recent progress in heavy atom-free triplet photosensitizers was summarized. The general approaches include attaining S1/Tn states sharing similar energy levels or proper molecular geometry to satisfy the angular momentum reservation in intersystem crossing (ISC). ISC via the higher singlet excited state (Sn, n > 1) → Tm (m > 1), which is a rarely reported phenomenon, was also discussed. The ISC of some Bodipy dimers was proposed to be via the 'doubly excited state', but recent studies show that the ISC mechanism of these Bodipy dimers is charge separation/recombination. These new findings in the study of triplet photosensitizers are useful for photovoltaics, photodynamic therapy and photocatalysis, as well as in fundamental photochemistry studies.

Making triplets from photo-generated charges: observations, mechanisms and theory

“…39 42 For more information on recent work on BODIPY molecules and their triplet states we refer to some excellent review papers. [43][44][45] From the great variety of compounds presented above we tentatively select two molecules to discuss a unifying theme in section 5: the BAD compound 2 (see Fig. 3) and the BODIPY dimer d2 (see Fig.…”

Singlet oxygen generation by porphyrins and metalloporphyrins revisited: A quantitative structure-property relationship (QSPR) study

“…However, incorporation of heavy atoms can lead to other problems, such as higher costs, toxicity, lower photostability and also a shortened triplet state lifetime [30]. These issues have stimulated much efforts in the field and photosensitizers with efficient ISC in the absence of any heavy atoms are being actively investigated [31,32].…”

A novel drug–drug nanohybrid for the self-delivery of porphyrin and cis-platinum

“…3c and d). 33 Furthermore, the photostability was also characterized by UV-vis spectra aer exposure to natural light for 24 h. The absorbance of TCPP decreased by 43.9%, while that of PCNH decreased by only 11.8%; this implies that the photosensitizers can be effectively protected when integrated into the nanohybrid ( Fig. 4a and S7 in the ESI †).…”