Synthesis and Structure-Property Relationships of Phosphole-Based π Systems and Their Applications in Organic Solar Cells

Abstract

Phosphole is a chemically tunable heterole, and its π-conjugated derivatives are potential candidates for optoelectronic materials. This account describes recent developments in the synthesis and structure-property relationships of π-conjugated phosphole derivatives made by my research group. Thiophene-phosphole-styrene, phosphole-acetylene-arene, oligophosphole, polyphosphole, areno[c]phosphole, and phosphole-heterole π systems are synthesized using titanacycle-mediated metathesis and palladium-catalyzed cross-coupling reactions. The structural, optical, and electrochemical properties of selected compounds are discussed. Initial results on some applications of thiophene-phosphole copolymers, acenaphtho[c]phospholes, and amine-terthiophene-phosphole donor-π-acceptor dyes in organic solar cells are described. These results give valuable information and guidelines for designing new phosphorus-containing organic materials for molecular electronics.

An Unexpected “Step-Conjugated” Biphosphole via Unique P–P Bond Formation

“…1 Our group and others have utilized these modifications to produce compounds that exhibit highly desirable properties in electronics, stimuli response, and self-organization. [1][2][3][4][6][7][8][9] At the same time, because of its conjugation with the p backbone, the exocyclic P-R moiety can affect the electronics of the system directly.…”

A Convenient Synthesis of 1,2,4‐ and 1,3,4‐Azadiphospholes

“…[8] Moreover, p-conjugated six-membered phosphorus heterocycles [9][10][11] as well as non-aromatic five-membered rings, such as phospholesa nd their derivatives (e.g.,o xides, sulfides, transition metal complexes), are being extensively investigated as precursors or components of optoelectronic materials,s uch as organicl ight-emitting diodes, organic semiconductors, and organic solar cells. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] Azadiphospholes [28] are aromatic and electron-rich heterocycles, [29,30] which eventually may find applications in organic electronic materials, for example, as electron donors (n-dopants). [31] The relevant syntheticm ethods are rather limited, salts of the anionic four-memberedr ings [II] 2À ,[ III] À ,a nd [IV] À requires reactiono ft he initially formed phosphaketene with as econd equivalento fN a(OCP) leadingt oaformal [2+ +2] cycloaddition.…”

“…Another remarkable recent achievement is the activation of dihydrogen by 2,4,6‐tri‐ tert ‐butyl‐1,3,5‐triphosphabenzene, which proceeds without transition metals . Moreover, π‐conjugated six‐membered phosphorus heterocycles as well as non‐aromatic five‐membered rings, such as phospholes and their derivatives (e.g., oxides, sulfides, transition metal complexes), are being extensively investigated as precursors or components of optoelectronic materials, such as organic light‐emitting diodes, organic semiconductors, and organic solar cells …”

Phospholones from Diacetylenic Ketones: Synthesis, Properties, and Reactivity

“…Five-membered heterocycles containing double bonds in conjugation with exocyclic carbonyl groups, such as 3-pyrrolone, 3­(2 H )-furanone, and thiophene-3­(2 H )-one (Figure ), are important intermediates in the synthesis of biologically active compounds that show high antitumor and antiviral activities as well as anti-inflammatory properties. − These heterocyclic subunits can be found in biologically active products such as vermelhotin, jatrophone, and geiparvarin and have recently drawn a lot of attention. ,, The phosphorus analogue of these heterocycles, 1,2-dihydro-3 H -phosphol-3-one, has made only sporadic appearances in the literature , and has been studied in much less detail due to its complicated synthesis. On the other hand, another 5-membered phosphorus heterocycle family, the 1 H -phospholes, is well-known and believed to be highly promising for applications including optoelectronic materials, , organic light-emitting diodes and organic field-effect transistors, − and organic solar cells. − Interest in the 1 H -phospholes is enhanced by the possibility of fine-tuning their optical properties by modifying the tetrahedral phosphorus center. The geometry of this phosphorus atom does not allow conjugation of the phosphorus lone pair with the butadiene unit, with the low aromaticity of the phospholes being attributable to hyperconjugation of the exocyclic σ*-orbital with the butadiene fragment .…”