Phosphorous‐Functionalized Bis(acyl)phosphane Oxides for Surface Modification

Abstract

Got a light? An efficient method for the synthesis of phosphorus‐functionalized bis(acyl)phosphaneoxides (BAPOs) was developed, which allows the preparation of photoactive polymers or grafting of these photoinitiators to various surfaces. Irradiation in the presence of polymerizable monomers leads to coatings that can be deposited imagewise.

Extending the Scope of Bis(acyl)phosphane Oxides: Additional Derivatives

“…These two molecules interact via intermolecular π‐stacking between the mesityl rings, which are at about 3.7 Å from each other. As also observed for other BAPOs and the commercially available Irgacure® 819, the distances between the carbon centers of the COMes groups and the phosphorus atom are unusually long [P1–C11 1.905(2) Å, P1–C1 1.895(1) Å], and are even longer than the P–C21 bond [1.832(2) Å], although the latter contains an sp 3 valence‐electron‐hybridized carbon center, while the acyl groups contain sp 2 carbons to which shorter bonds are expected. In contrast to other BAPO derivatives, which show skewed arrangements between the P=O unit and the COMes groups, the COMes groups in 1 are in almost parallel arrangement, and point to the opposite direction, with respect to the central P=O unit.…”

“…The new BAPO derivatives 1 – 5 were synthesized, as shown in Scheme , using a synthesis method that we reported briefly in a previous communication . The readily available sodium bis(mesitoyl)phosphide, Na[P(COMes) 2 ] (Mes = 2,4,6‐trimethylphenyl) was reacted with a hydrocarbon halide, R–X, in dimethoxyethane (DME) as the solvent, in a temperature range between 25 °C and 60 °C, to cleanly give the corresponding bis(acyl)phosphanes, R‐P(COMes) 2 , which were characterized by their characteristic 31 P NMR spectroscopic chemical shifts in the range 40–70 ppm [R = 1‐phenylethyl: 31 P NMR δ = 71.1 ppm; R = 1‐naphthylmethyl: 31 P NMR δ = 52.9 ppm; R = 2‐(2‐methoxyethoxy)ethyl: 31 P NMR δ = 44.9 ppm; R = 3‐bromopropyl: 31 P NMR δ = 48.5 ppm; R = 3‐(triethoxysilyl)propyl: 31 P NMR δ = 50.8 ppm].…”

“…Bis(acyl)phosphane oxides (BAPOs) have been among the most successful initiators for photoinduced radical polymerizations . Photolysis of BAPOs leads to the formation of a phosphanoyl and a mesitoyl radical via triplet‐state α‐cleavage, with high quantum yields (Scheme ) , .…”

“…To this end, several modifications, particularly at the phenyl substituents of the benzoyl moieties, have been introduced . Advanced synthetic protocols, however, allow the attachment of various groups directly at the phosphorus atom of BAPOs , . Here, we introduce five new BAPO derivatives, and besides describing their synthesis, we report on their optical spectra, α‐cleavage reactions, the kinetics of their addition to double bonds, their reduction potentials, and the EPR spectra of selected one‐electron‐reduced species.…”

Unprecedented Bifunctional Chemistry of Bis(acyl)phosphane Oxides in Aqueous and Alcoholic Media

“…Recently, water‐soluble BAPO derivatives have been utilized to efficiently form functional polymers in aqueous media and at interfaces (e.g. in the fields of hydrogel production, inkjet printing, cell encapsulation, and 3D printing) . Upon the photolysis of BAPOs in the presence of alcohols, time‐resolved EPR spectra have been reported, and phosphorus‐containing radicals have been assigned to the EPR data (for details, see Chapter 10 in the Supporting Information) …”