Influence of Anion Delocalization on Electron Transfer in a Covalent Porphyrin Donor–Perylenediimide Dimer Acceptor System

Photodriven electron transfer from a donor excited state to an assembly of electronically coupled acceptors has been proposed to enhance charge transfer efficiency in functional organic electronic materials. However, the circumstances under which this may occur are difficult to investigate in a controlled manner in disordered donor–acceptor materials. Here we investigate the effects of anion delocalization on electron transfer using zinc <i>meso</i>-tetraphenylporphyrin (ZnTPP) as a donor and a perylene-3,4:9,10-bis­(dicarboximide) dimer as the acceptor (PDI₂). The PDI units of the dimer are positioned in a cofacial orientation relative to one another by attachment of the imide group of each PDI to the 4- and 5-positions of a xanthene spacer. Furthermore, the distal imide group of one PDI is linked to the <i>para</i>-position of one ZnTPP phenyl group to yield ZnTPP-PDI₂. The data for the dimer are compared to two different ZnTPP-PDI monomer reference systems designed to probe electron transfer to each of the individual PDI molecules comprising PDI₂. The electron transfer rate from the ZnTPP lowest excited singlet state to PDI₂ is increased by 50% relative to that in ZnTPP-PDI, when the data are corrected for the statistics of having two electron acceptors. Femtosecond transient IR absorption spectroscopy provides evidence that the observed enhancement in charge separation results from electron transfer producing a delocalized PDI₂ anion

Probing Distance Dependent Charge-Transfer Character in Excimers of Extended Viologen Cyclophanes Using Femtosecond Vibrational Spectroscopy

Facile exciton transport within ordered assemblies of π-stacked chromophores is essential for developing molecular photonic and electronic materials. Excimer states having variable charge transfer (CT) character are frequently implicated as promoting or inhibiting exciton mobility in such systems. However, determining the degree of CT character in excimers as a function of their structure has proven challenging. Herein, we report on a series of cyclophanes in which the interplanar distance between two phenyl-extended viologen (<b>ExV</b>^<b>2+</b>) chromophores is varied systematically using a pair of <i>o</i>-, <i>m</i>-, or <i>p</i>-xylylene (<i><b>o</b></i>-, <i><b>m</b></i>-, or <i><b>p</b></i><b>-Xy</b>) covalent linkers to produce <i><b>o</b></i><b>-ExBox</b>^<b>4+</b> (3.5 Å), <i><b>m</b></i><b>-ExBox</b>^<b>4+</b> (5.6 Å), and <i><b>p</b></i><b>-ExBox</b>^<b>4+</b> (7.0 Å), respectively. The cyclophane structures are characterized using NMR spectroscopy in solution and single-crystal X-ray diffraction in the solid state. Femtosecond transient mid-IR and stimulated Raman spectroscopies show that the CT contribution to the excimer states formed in <i><b>o</b></i><b>-ExBox</b>^<b>4+</b> and <i><b>m</b></i><b>-ExBox</b>^<b>4+</b> depends on the distance between the chromophores within the cyclophanes, while in the weak interaction limit, as represented by <i><b>p</b></i><b>-ExBox</b>^<b>4+</b> (7.0 Å), the lowest excited singlet state of <b>ExV</b>^<b>2+</b> exclusively photo-oxidizes the <i><b>p</b></i><b>-Xy</b> spacer to give the <i><b>p</b></i><b>-Xy</b>^<b>+•</b>-<b>ExV</b>^<b>+•</b> ion pair. Moreover, the vibrational spectra of the excimer state show that it assumes a geometry that is intermediate between that of the locally excited and CT states, approximately reflecting the degree of CT character

A Cellular Anatomy of the Normal Adult Human Prostate and Prostatic Urethra

Summary: A comprehensive cellular anatomy of normal human prostate is essential for solving the cellular origins of benign prostatic hyperplasia and prostate cancer. The tools used to analyze the contribution of individual cell types are not robust. We provide a cellular atlas of the young adult human prostate and prostatic urethra using an iterative process of single-cell RNA sequencing (scRNA-seq) and flow cytometry on ∼98,000 cells taken from different anatomical regions. Immunohistochemistry with newly derived cell type-specific markers revealed the distribution of each epithelial and stromal cell type on whole mounts, revising our understanding of zonal anatomy. Based on discovered cell surface markers, flow cytometry antibody panels were designed to improve the purification of each cell type, with each gate confirmed by scRNA-seq. The molecular classification, anatomical distribution, and purification tools for each cell type in the human prostate create a powerful resource for experimental design in human prostate disease. : Using single-cell RNA sequencing, immunofluorescence, and flow cytometry, Henry et al. create a cellular anatomy of the normal human prostate and provide the tools to identify, isolate, and localize every cell type. They identify two additional epithelial cell types enriched in the prostatic urethra and proximal prostatic ducts. Keywords: human prostate, zonal anatomy, single-cell RNA sequencing, flow cytometry, prostate cancer, benign prostatic hyperplasia, human cell atlas, prostate epithelia, prostate stroma, GUDMA