Supramolecular Dynamics Studied Using Photophysics

Abstract

Dynamics is an essential feature of supramolecular systems, and it's understanding will be central in achieving new chemical function. The methodology to obtain association and dissociation rate constants for fast binding of guests to host systems in real time is described. Examples are provided for binding of guests to cyclodextrins or bile salt aggregates with an emphasis on the type of information and mechanistic insight that can only be uncovered from kinetic studies and is not apparent in thermodynamic investigations.

Dynamics of Supramolecular Association Monitored by Fluorescence Correlation Spectroscopy

“…The normalized autocorrelation function G(t) of the intensity fluctuations dF(t) = F(t)ÀhFi indicates the probability to register from the same molecule a second photon after the correlation time t, once a first photon is emitted, as shown in Equation (1) [see Figure 3 www.chemphyschem.org…”

“…While more and more structural information can be obtained, much less is known about the interplay between structure and dynamics. [1] At the same time, highly complex supramolecular systems can now be synthesized, and the understanding of the underlying dynamics is essential for the design and control of their function. [2] Measuring these typically fast dynamics is challenging.…”

“…Several fast techniques have been used so far to determine rate constants of supramolecular association/dissociation. Their application to cyclodextrin host-guest inclusion has been reviewed in detail by Bohne et al [1,5,6] and their use for the study of surfactant self-assemblies by Zana. [7] Frequently used fast techniques are temperature jump (T-Jump), time-resolved fluorescence (TRF), laser flash photolysis (LFP), and ultrasonic relaxation.…”

“…As pointed out by Bohne [1] there is a need for methodologies which cover a very wide range of time scales, ideally within the same experiment. It is also preferred not to rely on long-lived triplet states or competitive quenching and to avoid perturbation of the system.…”

Propiedades Fotoquimicas De Farmacos Que Contienen El Cromoforo Naftaleno en Medios Microheterogeneos.

“…Hay que destacar que la pendiente de la recta de la Como se puede observar en la Figura 6.6, el análisis de regresión de las cinéticas de desaparición se ajustaba a una línea recta para el NPXMe y el CIN, pero no para el PPN, lo cual se puede atribuir a la movilidad del estado excitado triplete entre MM y disolución. 202,203 Por tanto, la k q,MM para el PPN se recalculó, teniendo en cuenta un equilibrio dentro -fuera de la MM, utilizando un modelo descrito previamente en la literatura (Ecuación 6.2). Los resultados obtenidos en la desactivación del estado excitado triplete están de acuerdo con los obtenidos anteriormente mediante fluorescencia, demostrando así que la metodología basada en FDL es conveniente para evaluar el grado de encapsulamiento de fármacos en el interior de MM.…”