Tuning the Energy Gap by Supramolecular Approaches: Towards Near‐Infrared Organic Assemblies and Materials

Abstract

Near-infrared (NIR) organic materials are of great importance for both fundamental research and practical applications. While much effort has been taken to covalently design and synthesize NIR organic materials with a low energy gap, there are supramolecular approaches for tuning the energy gap to noncovalently fabricate NIR organic assemblies and materials. In this concept article, we summarize and discuss several supramolecular approaches, including the fabrication of charge transfer supramolecular complexes, the fabrication of supramolecular J-aggregates, and the fabrication of supramolecularly stabilized organic radicals. The nature of noncovalent interactions in supramolecular approaches can provide NIR organic assemblies and materials with unique properties such as reversibility, stimuli-responsiveness, recyclability, and adaptive abilities.

Fluorescent J-aggregates of cyanine dyes: basic research and applications review

“…Thus, the extension into near-IR spectral range can be quite successful; it allows creating new materials displaying the characteristic properties of J-aggregates that are highly needed for various applications [104]. Meantime, the description even in monomeric form of fluorescent properties of these dyes is lacking in many reports.…”

p‐Quaterphenylene as an Aggregation‐Induced Emission Fluorogen in Supramolecular Organogels and Fluorescent Sensors

“…This important research effort has been driven by the demandi nl uminescentw ell-orderedn anostructures widely used in light-emitting diodes (LEDs), field-effect transistors, optical sensors, etc. [1][2][3][4][5][6][7][8][9] To enhancet he stabilitya nd robustness of the sophisticateda ssemblies, multi-noncovalenti nteractions should be delicately incorporated by rational design on am olecular scale. [10][11][12][13][14] Various noncovalent interactions (such as hydrogen bonding, p-p stacking,a nd van der Waals forces) have been utilized to hold the small buildingb locks together, [15,16] and numerous artificial supramolecular architectures of different sizes, shapes, and functions have been achieved, [17][18][19][20][21][22][23][24][25][26] among which gelation is ap owerful methodl eading to welldefined supramolecular nanostructures.…”

Cocrystals Strategy towards Materials for Near‐Infrared Photothermal Conversion and Imaging

“…[5] To date, organic PT materials are mainly porphysome, [6] indocynine green, [7] and polymers such as polyaniline [8] and polypyrrole. [9] Driven by the desire to prepare more high-performance PT conversion materials,e xtensive efforts are paid from two aspects:one is to enhance IR absorption [10] through extending the molecular conjugation length or covalently linking electron-donor and electron-acceptor fragments, [11] and the other is to inhibit the radiative transition process [12] by enhancing the quenching effect or increasing the concentration of free radicals. [13] However,both the complicated design and tedious synthesis limited the development of organic PT areas.T herefore,i ti sn ecessary to develop new types of PT materials to meet the increasing PT application demands.…”