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Thermodynamics and 2 H NMR Study on the Insertion of Small Quinones into a Discotic Nematic Lyotropic Liquid Crystal
Author(s) -
BahamondePadilla Víctor Eduardo,
LópezCascales José Javier,
ArayaMaturana Ramiro,
MartínezCifuentes Maximiliano,
Weiss López Boris Enrique
Publication year - 2014
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201301146
Subject(s) - chemistry , liquid crystal , lyotropic , bilayer , lyotropic liquid crystal , molecule , deuterium , relaxation (psychology) , molecular dynamics , lipid bilayer , deuterium nmr , crystallography , nuclear magnetic resonance spectroscopy , stereochemistry , organic chemistry , computational chemistry , membrane , phase (matter) , materials science , psychology , social psychology , liquid crystalline , biochemistry , physics , optoelectronics , quantum mechanics
A detailed description of the distribution, interaction, and dynamics of molecules with biological activity dissolved in a hydrophobic bilayer, a simple model of a biological membrane, provides valuable information for a better understanding of drug functioning, which can be very useful in drug design. Here we present an 2 H NMR and molecular dynamics study on the insertion, distribution, interactions, and thermodynamics of two biologically active molecules, 9,10‐dihydroxy‐4,4‐dimethyl‐1,4,5,8‐tetrahydroanthracen‐1‐one (HQ), with anticancer activity, and 4,4‐dimethyl‐1,4,5,8,9,10‐hexahydroanthracen‐1,9,10‐trione (Q) a fungicide, dissolved in a nematic discotic lyotropic liquid crystal (ndllc) composed of sodium dodecylsulphate (SDS), decanol (DecOH) and Na 2 SO 4 in water. 2 H NMR quadrupole splittings (Δ ν Q ) and longitudinal relaxation times ( T 1 ) from HQ‐d 6 , Q‐d 4 , DecOH‐α‐d 2 , partially deuterated water, and SDS‐d 25 were measured and several molecular dynamics trajectories were also calculated. In particular, Δ G , Δ H , and Δ S profiles for the process of both molecules crossing the bilayer were estimated. It was evidenced that the insertion of both molecules into the aggregate is a spontaneous process, and the molecules are mainly distributed in the internal side of the interface. Addition of HQ or Q decreased the mobility of all aggregate components, but this effect was more pronounced for HQ. The rotational correlation time of Q allowed an estimate of 5.3 cP for the microviscosity inside the ndllc aggregate, in the order of previously measured values in similar environments. Both guest molecules display similar free‐energy profiles for the process of crossing the bilayer, with a calculated barrier height of 25 and 36 kJ mol −1 for HQ and Q, respectively.