2D Nanomaterial-Directed Molecular Aggregation and Energy Transfer between Edge-Bound Donor–Acceptor Pairs

Abstract

Forster resonance energy transfer (FRET) is a phenomenon that is observed between an excited energy donor and ground-state acceptor in close proximity. The efficiency of FRET varies with the distance and orientation of the donor−acceptor pair, solvent, and other competing processes. Layered silicates, with their ability to stack in "pillars" with a certain interlayer spacing, present a useful platform to influence the interactions of edge-bound groups. In this study, asymmetric perylene and naphthalene diimides were grafted to the edge of the layered silicate Laponite, and their photophysical properties and aggregation behavior were studied in different compositions of water and dimethylformamide. FRET was observed from naphthalene diimide-to perylene diimide-functionalized Laponite, and pillaring of Laponite with a cationic surfactant led to significantly enhanced FRET, which was attributed to the reorientation of chromophores due to the organized stacking of pillared particles. This study reports how ordering of the discoidal layered silicate nanoparticles into organized stacks can tune the aggregation of edge-bound FRET pairs. This can aid in understanding donor−acceptor interactions at the interface of anisotropic nanomaterials and improve control over the distance and orientation of donor−acceptor pairs and resulting energy transfer processes. Furthermore, this is the first example of the attachment of naphthalene diimides to layered silicate edge sites. This study opens the door to further studies of geometry-dependent energy flows in inorganic−organic hybrid materials and will advance applications in sensing, energy, and molecular electronics.

Investigating Solvent-Induced Aggregation in Edge-Functionalized Layered Silicates via All-Atom Molecular Dynamics Simulations

“…Seminal work by Song and reported the treatment of montmorillonite with trichloro and trialkoxysilanes to achieve high loading with little change to the basal spacing of the clay . This was followed by the coupling of methacrylate-terminated alkoxysilanes to the clay edge, and an important observation from this study was that trialkoxysilanes led to the “pillaring” or linkage of sheets together, whereas monoalkoxysilanes provided edge modification while retaining water dispersibility. , This was confirmed in further studies by Wheeler and coworkers, which firmly established the conditions for successful modification of the laponite clay edge and set the stage for the next decades of research on nanocomposites based on covalently functionalized clays. , Recently, the linkage of chromophores on layered silicate edges has provided a unique approach to modulating the self-assembly and photophysical properties of such nanohybrids, opening the door to applications in healthcare and sensing. , However, computational tools for studying such nanohybrids are currently lacking.…”

The Role of Aggregation on Energy Transfer in Layered Rare-Earth Hydroxide/Naphthalene Diimide Hybrid Materials

“…The observation that doping of LREHs with elements (such as LYH with Ce in the present study) alters the kinetics of molecular aggregation is useful for designing future organic–inorganic hybrids for energy transfer. Layered materials have already shown great potential for designing energy transfer strategies between molecular donor–acceptor pairs, particularly those based on rylene diimides, which are driven in part by aggregation state. , These results further suggest that the aggregation modes of fluorophores bound to luminescent nanomaterials are also critical to control energy transfer between particle and molecule. These hybrid materials are expected to expand the field of LREHs, and lead to improved understanding of other organic–inorganic hybrids, advancing applications in energy harvesting, optoelectronics, sensing, and bioimaging.…”

Bubble Printing of Layered Silicates: Surface Chemistry Effects and Picomolar Förster Resonance Energy Transfer Sensing

“…The results of the FRET sensing experiments suggest that further avenues to exploit the adsorption of analytes should be sought. The potential to independently modify the basal surfaces noncovalently and the edge sites covalently provides many potential synthetic approaches to link biomolecules or other targets for selective sensing via several different modes of sensing . The large detection range across concentrations down to picomolar levels can benefit a variety of target analytes.…”