Dithienophosphole‐Based Phosphinamides with Intriguing Self‐Assembly Behavior

Abstract

A new, highly adaptable type of phosphinamide‐based hydrogen bonding is representatively demonstrated in π‐conjugated phosphole materials. The rotational flexibility of these intermolecular P=O−H−N hydrogen bonds is demonstrated by X‐ray crystallography and variable‐concentration NMR spectroscopy. In addition to crystalline compounds, phosphinamide hydrogen bonding was successfully introduced into the self‐assembly of soft crystals, liquid crystals, and organogels, thus highlighting the high general value of this type of interaction for the formation of organic soft materials.

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

“…1,12 Second, although not very pronounced, the peak positions are also quite close to those of 8, which by contrast shows two fairly pronounced absorption peaks at 315 and 365 nm. The latter peak coincides with the p-p* transition of previously studied dithienophosphole oxides, 3,12,13 suggesting a localized transition within this half of the molecule; the peak at 315 nm appears to originate from a localized transition likely involving the trivalent phosphole subunit.…”

“…Mono-oxidation can be achieved by treating 4 with 1 equiv of bis(trimethylsilyl)peroxide ((Me 3 SiO) 2 ). However, further oxidation of the monoxide 8 led to the cleavage of the P-P bond, which is known for related species from the literature, 25 and the formation of the previously reported phosphinic acid 9 13 was observed (Scheme 4, top). Oxidation of 8 with air was not successful either, given that prolonged exposure to air only led to its decomposition.…”

“…In a previous study on the self-assembly behavior of p-conjugated phosphinamides, the P-amino-dithienophosphole precursor 1 was synthesized according to our reported methods (Scheme 1), and functionalization provided a series of phosphinamides with unique hydrogen-bond-based self-organization and photophysical properties. 13 To further expand the scope of the P-amino-phosphole chemistry, we functionalized 1 by oxidation to give 2, and reaction with BH 3 provided 3. However, we always encountered difficulties in obtaining the trivalent species 1 cleanly.…”

“…13 C{ 1 H} NMR (101 MHz, chloroform-d) d 146.28 (d, J = 12.1 Hz), 141.74 (d, J = 3.8 Hz), 127.10 (d, J = 19.1 Hz), 125.42 (d, J = 5.5 Hz), 50.04 (d, J = 9.4 Hz), 26.46 (d, J = 5.1 Hz); HRMS (ESI+) m/z: [M + H] + calcd 266.0222, found 266.0220. 1…”

One Step Forward: A Novel “Step-Conjugated” Biphosphole

“…6 In this issue of Chem, Dobrovetsky, Baumgartner, and coworkers report the discovery of a previously unknown bi(dithienophosphole) scaffold with an interesting molecular and electronic architecture arising from a novel P-P bond-forming reaction between P-aminophospholes. 7 Baumgartner and coworkers had previously directed research toward P-aminophospholes as building blocks for the synthesis of varied phosphole derivatives, 8 but in their current work, Fortuna's hand weighed heavily on the rudder, given that attempted purification of P-amino-dithienophosphole 1 by column chromatography on alumina unexpectedly led to the precipitation of crystalline material. Surprisingly, single-crystal X-ray crystallographic analysis showed the product to be bi(dithienophosphole) 2 (Scheme 1A).…”