A bifurcated molecular pentad capable of sequential electronic energy transfer and intramolecular charge transfer

Abstract

An extended molecular array, comprising three distinct types of chromophores and two additional redox-active subunits, that harvests photons over most of the visible spectral range has been synthesized and characterised. The array exhibits a rich variety of electrochemical waves when examined by cyclic voltammetry but assignment can be made on the basis of control compounds and molecular orbital calculations. Stepwise electronic energy transfer occurs along the molecular axis, corresponding to a gradient of excitation energies, to populate the lowest-energy excited state of the ultimate acceptor. The latter species, which absorbs and emits in the far-red region, enters into light-induced charge transfer with a terminal amine group. The array is relatively stable under illumination with white light but degrades slowly via a series of well-defined steps, the first of which is autocatalytic. One of the main attributes of this system is the capability to harvest an unusually high fraction of sunlight while providing protection against exposure to UV light.

Development of an Inner Filter Effects-Based Upconversion Nanoparticles–Curcumin Nanosystem for the Sensitive Sensing of Fluoride Ion

“…As shown in Figure A, the intensity of UV absorption peak at 417 nm decreased gradually whereas a new UV absorbance peak at 560 nm was found clearly to increase with the increasing concentration of F – . These two changes were attributed to the involvement of −OH groups and the intramolecular charge transfer transition between the curcumin–F – complex, respectively . A linear response of the mixed nanosystem between the absorption and the F – can be obtained at F – concentration range of 5–200 μM.…”

“…These two changes were attributed to the involvement of −OH groups and the intramolecular charge transfer transition between the curcumin−F − complex, respectively. 31 A linear response of the mixed nanosystem between the absorption and the F − can be obtained at F − concentration range of 5−200 μM. It can be seen that within the range of 5−25 μM, the linear relationship (red standard curve in Figure 5B) between the concentration of F − and absorbance at 560 nm was not obvious, so the colorimetric method cannot easily achieve the detection when the F − is below 25 μM.…”

Dramatic Effect of Solvent on the Rate of Photobleaching of Organic Pyrrole‐BF2 (BOPHY) Dyes

“…Despite the rising importance of molecular-based photochemicald evices, the underlying mechanismsf or light-promoted degradation of organic dyesh ave not been explored fully and the likely inclusiono fa utocatalysis complicates kinetic studies. [20] Such experimental research is essential, however,i f advanced materials are to be identified in ar ational and timely manner.I nn atural photosynthetic organisms, by contrast, evolution has led to the development of elaborate protective systems to stabiliset he light-harvestingm achinery against overexposure to sunlight [21] and also to prevent damage caused by reactive intermediates. [22] Natural systems furtherb enefitf rom self-repair mechanisms, [23] such as that provided by the photolyase enzyme, [24] that are well outside the capability of artificial solar concentrators based on molecularm aterials.…”

FRET on Surface of Silica Nanoparticle: Effect of Chromophore Concentration on Dynamics and Efficiency

“…4−6 The preparation of light harvesting antennae often involves elaborate chemical synthesis. 3,7 This requirement can be circumvented by employing matrices 8−11 that can act as scaffolds supporting ordered arrangements of molecules and thus leading to efficient light harvesting. 12 Our interest in this context is to design light harvesting antennae that utilize silica nanostructures 13−15 as scaffolds and to study the excited state dynamics in these systems.…”

“…The potentials of a myriad of molecular, supramolecular, and nanomolecular systems are being explored in the quest for ideal light harvesting antennae. Some examples of such systems are porphyrin arrays, , dendrimers, nanostructures, and nanoconjugates. − The preparation of light harvesting antennae often involves elaborate chemical synthesis. , This requirement can be circumvented by employing matrices − that can act as scaffolds supporting ordered arrangements of molecules and thus leading to efficient light harvesting . Our interest in this context is to design light harvesting antennae that utilize silica nanostructures − as scaffolds and to study the excited state dynamics in these systems.…”