Nanoreactors based on amphiphilic uracilophanes: self-organization and reactivity study.
New amphiphilic pyrimidinic macrocycles (APMs) with two (APM-1) and three (APM-2) decyl tails have been synthesized by quaternization of the bridged N. Complex examination of the APM-based systems with the help of tensiometry, conductometry, dynamic light scattering, and UV and NMR spectroscopy provides evidence for their aggregation. Calculations based on surface tension isotherms and on packing parameter considerations make it possible to assume a lamellar packing of macrocycles when aggregating. Marked differences in the aggregation behavior of APM-1 and APM-2 have been found. The additives of polyethylenimine (PEI) exert little influence on the critical micelle concentration (cmc) of APM-1, while in the APM-2/PEI systems there occurs a pronounced decrease in the cmc and also a ca. 2-fold decrease in the surface area per molecule. The APM-based assemblies are explored as nanoreactors for the hydrolysis of O-alkyl O-p-nitrophenyl (chloromethyl)phosphonates (alkyl = ethyl, hexyl). The kinetic study reveals a minor rate effect of the APM-1-based systems. In the APM-2-based systems an acceleration of the hydrolysis of both phosphonates occurs as compared to the uncatalyzed process. Within the APM-2 --> APM-2/PEI --> APM-2/PEI/La(III) series, due to the cooperative contributions of the supramolecular, polymer, and homogeneous catalysis, an increase in the catalytic effect is observed from 30 times to 3 orders of magnitude as compared to that of the basic hydrolysis of the substrates.
Zakharova
Lucia Ya
LY
A. E. Arbuzov Institute of Organic and Physical Chemistry of the Russian Academy of Sciences, 8 ul. Akad. Arbuzov, Kazan 420088, Russia. lucia@iopc.knc.ru
Semenov
Vyacheslav E
VE
Voronin
Mikhail A
MA
Valeeva
Farida G
FG
Ibragimova
Alsu R
AR
Giniatullin
Rashid Kh
RKh
Chernova
Alla V
AV
Kharlamov
Sergey V
SV
Kudryavtseva
Lyudmila A
LA
Latypov
Shamil K
SK
Reznik
Vladimir S
VS
Konovalov
Alexander I
AI