New insights into prediction of weak π-π complex association through proton-nuclear magnetic resonance analysis.

For analysis of weak π-π complexes proton-nuclear magnetic resonance (proton-NMR) simultaneously provides information of stacking configurations and association constants [Formula: see text] However, an apparent issue for this approach is inconsistent/impossible constant estimation which often leads to unreasonable interpretation for π-π complexation. Whether or not this proton-dependent constant variation could be attributed to simple experimental uncertainties or to more sophisticated additional unspecific shielding effects (AUS effects) was addressed by means of hypothesis tests using a robust bootstrap technique in this report. Our analysis shows the significance of AUS effects on such variation in constant estimation.

Pi-Pi complexation of bupivacaine and analogues with aromatic receptors: implications for overdose remediation.

The interaction of the important but often overdosed local anesthetic bupivacaine, its structural analogs 2,6-dimethylaniline, and N-methyl-2,6-dimethylacetanilide, and cocaine, with several electron deficient aromatic moieties were studied primarily by proton NMR and UV-visible spectroscopy. In solution, the anesthetic, its analogs and cocaine are electron donors and form pi-pi charge transfer complexes with strong aromatic acceptors, as monitored by the upfield changes induced in the NMR chemical shifts (delta) and red-shifted UV-vis wavelength (lamda max) absorbance of the acceptors. The equilibrium binding constant, K, was determined from the 1H NMR charge transfer induced chemical shift changes and used to calculate the free energy (deltaG) for complex formation of three acceptor-donor pairs.

Graft polymerization of styrene initiated by covalently bonded peroxide groups on silica.

The graft polymerization of styrene initiated by immobilized peroxide groups was investigated. Three different types of modification reactions were used to introduce peroxide groups which are directly attached onto the surface of two different silica supports. Silanol groups were chlorinated using thionyl chloride or tetrachlorosilane.

Preparation and characterization of polymer composite multilayers on SiO2.

Poly(diallyldimethylammonium chloride) (PDADMAC) and poly(sodium 4-styrenesulfonate) (PSS) have been consecutively adsorbed onto 1.5-microm charged silica (SiO2) particles. Time-dependent adsorption studies indicate that, due to the strong ionic charge of the dissociated polycation in water, adsorption is complete in less than 30 min.

Aromatic-aromatic interaction of amitriptyline: implication of overdosed drug detoxification.

The objectives of this work are to explore the pi-pi complexation of amitriptyline with pi electron-deficient aromatic rings and demonstrate the feasibility of pi-pi complexation for overdosed drug detoxification. Water-soluble oligochitosan was chemically modified with dinitrobenzenesulfonyl groups to induce selective binding toward amitriptyline through pi-pi complexation. NMR studies showed that benzenesulfonyl and dinitrobenzenesulfonyl protons were upfield shifted by the addition of amitriptyline, indicating the formation of pi-pi complexes.