Synthesis and Optical and Electronic Properties of Core-Modified 21,23-Dithiaporphyrins

Abstract

Core-modified 21,23-dithiaporphyrins, meso-substituted with both electron-withdrawing 4-phenylcarboxylic acids and related butyl esters, and electron-donating phenyldodecyl ethers were synthesized. The porphyrins displayed broad absorbance profiles that spanned from 400 to 800 nm with molar absorptivities ranging from 2500 to 200000 M(-1) cm(-1). Electrochemical experiments showed the dithiaporphyrins undergo two consecutive, one-electron, quasi-reversible oxidations and reductions at -1.78, -1.43, 0.63, and 0.91 V versus a ferrocene/ferrocenium internal standard. Spectroelectrochemistry and cyclic voltammetry revealed the dithiaporphyrins are stable and can endure many cycles of oxidation and reduction without signs of decomposition. The electronics of the two dithiaporphyrins were similar, and DFT calculations showed the HOMO-LUMO energy difference was smaller than tetrapyrrolic porphyrin analogues. Overall, the combination of desirable electronics, namely: quasi-reversible oxidations and reductions as well as broad absorbance profiles, combined with stability, imply that these core-modified 21,23-dithiaporphyirns could be potentially used as an ambipolar material for organic electronic applications.

Metal-Free Trifluoromethylation of Aromatic and Heteroaromatic Aldehydes and Ketones

“…1 H NMR (400 MHz, CDCl 3 ) δ 10.10 (s, 1H), 8.19 (d, J = 8.3 Hz, 2H), 7.95 (d, J = 8.2 Hz, 2H), 4.36 (t, J = 6.6 Hz, 2H), 1.81–1.74 (m, 2H), 1.53–1.44 (m, 2H,), 0.99 (t, J = 7.4 Hz, 3H). Spectroscopic data are consistent with the previous report …”

Construction of Novel Cyclic Tetrads by Axial Coordination of Thiaporphyrins to Tin(IV) Porphyrin

“…The relaxed equilibrium DFT structures are presented in Figures and , and the corresponding structural parameters are shown in Tables and . The bond lengths and angles in the relaxed DFT structures of the monomers (Figure and Tables and ) are in good agreement with the respective X-ray crystal structures − and calculated structures in the literature. − A notable feature of the tin­(IV) ion in monomer 9 is that it displayed a distorted octahedral geometry, where the O–Sn–O bond was tilted toward the mean plane of the macrocycle (Table ), which is also in agreement with X-ray crystal and computational structures. ,, …”

Pi-Extended Ethynyl 21,23-Dithiaporphyrins: A Synthesis and Comparative Study of Electrochemical, Optical, and Self-Assembling Properties

“…Typically, porphyrins with less than four meso -arylethynyl substituents are synthesized via reaction of TIPS-propynal and subsequent Sonogashira cross-couplings. ,− Dithiaporphyrin synthesis involves a synthetic route from 2,5-thiophene diols, − , shown in Scheme , prior to the final macrocyclic ring-closing step. This diol formation synthetic step permits a cleaner macrocyclization reaction, resulting in easier purification because scrambling is largely suppressed.…”

“…As such, the following derivatives were synthesized: one with a weakly electron-donating alkyl group and one with a strong electron-donating ether group. Scheme S1 (see Supporting Information (SI)) shows the synthetic details, which afforded the ethynyl precursors 1a and 1b that were previously reported. , Briefly, the synthesis of the strong electron-donating substituent begins by alkylating 4-bromophenol as described in our previous synthetic work , to obtain 1-bromo-4-(dodecyloxy)­benzene. The weakly electron-donating 1-bromo-4-dodecylbenzene was obtained by a Friedel–Crafts acylation of bromobenzene with dodecanoyl chloride followed by a Wolff–Kishner reduction .…”

“…For applications in organic photovoltaics, improved properties include the following: bathochromically shifted absorbance profile to harvest low energy photons; lowered oxidation potentials to become stronger donor materials; and an attempt to impart long-range ordering on these materials through liquid crystalline phases. Core-modified 21,23-dithiaporphyrins, for example, have shown enhanced visible light absorption and facile redox properties compared to their nitrogen counterparts. − Recently, porphyrins have appeared in the materials community as highly efficient, even world-leading, components in photovoltaic power conversion efficiencies. Many of the highest performance compounds employ the “donor–acceptor” or “push–pull” approach to porphyrins, which are achieved through two sequential Sonogashira cross-coupling reactions of ethynyl moieties carried out after the porphyrin ring-closing step. ,− Under standard porphyrin synthesis conditions involving an aryl-aldehyde and pyrrole in the presence of a Lewis acid, the yields are usually low, as such, there are practical motivations to avoid postporphyrin modifications.…”