A method for analysis of multicomponent systems of interacting aromatic molecules in solution

Abstract

A method has been developed for analyzing multicomponent mixtures containing N different types of noncovalently interacting aromatic molecules using spectroscopic data [nuclear magnetic resonance (NMR), UV-vis, fluorescence, circular dichroism]. The method is based on an algorithmical approach to modeling of the N-component dynamic equilibrium (N-STOCH algorithm), dealing with numbers in N-based numerical systems as analogs of molecular complexes being formed in solution. A basic property of the algorithm is the ability to incorporate any known specificity of molecular interactions without constructing complex mathematical formulas. The utility of the N-STOCH algorithm was demonstrated by using as an example the NMR investigation of the dissociation of a heteroassociation complex of two anticancer drugs on addition of caffeine.

General statistical-thermodynamical treatment of one-dimensional multicomponent molecular hetero-assembly in solution

“…The use of such equations in the description of experimental data may follow the standard algorithm reviewed in Refs. [24,25] and currently being used by many authors in applications concerning molecular assembly. We shall briefly describe this algorithm without going into its details.…”

“…accounts for all possible arrangements of molecules of different types. The whole set of possible complexes also includes the pairs of mirror symmetrical complexes (for example, complexes of C j K ji C i K ii C i and C i K ii C i K ij C j type) which have been previously denoted as 'reflected' complexes [18,24,25]. They become physically indistinguishable under the condition K ij ¼ K ji , which is the case most frequently met in one-dimensional hetero-assembly in solution (account of the distinguishability, K ij -K ji , was accomplished in Ref.…”

“…of molecules of the ith type is represented as an additive quantity (for example, see Refs. [17][18][19][20][22][23][24][25][26]), which can be obtained by the averaging of particular observables, n Another assumption commonly used in analysis of a onedimensional assembly is the approximation of 'nearest neighbour', which considers that only the nearest molecules (in direct contact with the i-type molecule in a complex) influence the n 0i of that molecule (for example, see Refs. [17,18,22,24]).…”

“…[17]) and have recently been overcome for two-component hetero-assembly [24]. The closest approaches to similar solutions for multicomponent systems have been suggested using the algorithmic approach [25], transfer matrix formalism [22] and sequence generating function formalism [26]. However, these solutions are all incomplete, viz.…”

“…However, these solutions are all incomplete, viz. the algorithmic approach [25] is limited by the finite lengths of aggregates, the transfer matrix approach [22] does not treat 'reflected' complexes at all and therefore considers experimental observable incorrectly and the sequence generating function approach [26] fully accounts for the 'reflected' complexes but does not provide 0301-0104/$ -see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.chemphys.2013.06.006 a link to experimental observables.…”