Hydrophobic Thin Layers Based on N-Coordinated Metallaboroxine Polymers

Abstract

The reaction of organogallium amide LGa(NEt2)2 (1) and organotin carbonate L(Ph)SnCO3 (2), where L = 2,6-(Me2NCH2)2C6H3, with organoboronic acids RB(OH)2 yielded molecular gallium- and stannaboroxines LM(O3B2R2) (3-8) (3: M = Ga, R = 4-tBu-C6H4; 4: M = Ga, R = 4-CF3-C6H4; 5: M = Ga, R = 3,5-(CF3)2-C6H3; 6: M = PhSn, R = 4-tBu-C6H4; 7: M = PhSn, R = 4-CF3-C6H4; 8: M = PhSn, R = 3,5-(CF3)2-C6H3). The Lewis acidity of boron atom (especially in 8) allowed to form N -> B coordination bond with bases such as 4-Me2N-pyridine (DMAP) or poly(4-vinylpyridine-co-styrene) (PVPS) yielding new compounds DMAP -> 8 (9) and PVPS -> 8 (10). The good film forming properties of 10 allowed the deposition of transparent thin layers by spin-coating method and the determination of their hydrophobic properties by the sessile drop method. The study of hydrophobicity was subsequently focused on the content of stannaboroxine 8 in PVPS and on the concentration influence of the deposited PVPS:8 mixture solution. The parameters of thin layers such as thickness, transparency, and roughness were also determined.