Molecular crystalline materials with tunable luminescent properties: from polymorphs to multi-component solids

Abstract

Tuning and controlling the luminescent properties of molecular materials by changing the orientation and arrangement of the fluorophores within a solid has played an important role in realizing multi-color emission. The formation of polymorphs and multi-component molecular solids have attracted considerable interest as new ways of achieving controllable luminescence and other photophysical properties for application in the next generation of photofunctional materials. In this article, recent advances in the synthesis of fluorescent polymorphs and multi-component materials and potential photo-related applications of the resulting materials are described. We first review the methods of preparation of polymorphs with tunable static luminescence, and the switching of the dynamic luminescence between polymorphs for potential sensor applications is also introduced. Attention is then focused on the supramolecular design (making use of hydrogen bonding and halogen bonding interactions) and methods of fabrication of multi-component molecular solids, and their color-tunable fluorescence and phosphorescence together with their stimuli-responsive properties for use as sensors.The use of density functional theory to study intramolecular and intermolecular energy transfer as well as the electronic structures of multi-component molecular solids is also outlined. Finally, we briefly discuss perspectives for the further development of these luminescent molecular solid-state materials. Dongpeng Yan obtained hisPhD degree under the supervision of Prof. Xue Duan at Beijing University of Chemical Technology (BUCT) in 2012, In 2011, as a visiting student, he studied at the Department of Chemistry, University of Cambridge under Prof. William Jones. Now he is an associate professor at BUCT. His main research topics are experimental and computer simulation studies of organic photofunctional crystals and new layered materials. He was received an Award Nomination of Annual Figure among Chinese University Students (2011), a "Talent Model" Award in the Universities in Beijing (2010), the Tang Aoqing Chemical Scholarship (2011), and many other awards. David G. Evans studied as both undergraduate and research student at Jesus College, Oxford and obtained a DPhil under the supervision of Prof. D. M. P. Mingos FRS. Aer postdoctoral work at Bristol University with Prof. F. G. A. Stone FRS, he was appointed to a lectureship at Exeter University in 1985. Several visits to Chinese university chemistry departments in the early 1990s convinced him of China's great potential for development in this area and he moved to Beijing University of Chemical Technology in 1996. His research interests focus on intercalation in layered solids. He was awarded an International Scientic and Technological Cooperation Award of the People's Republic of China in 2005.

Fabrication and Investigation of 26NCA Films Exhibiting Tunable Blue Fluorescence Based on LVPVDM

“…In addition, In is mainly used in the production of ITO target materials due to its strong light permeability and electric conductivity. However, little attention has been focused on the tunable fluorescence of micro/nanostructured single/twocomponent metallic/organic fluorescent films, which are expected to be used in large-scale flat panel display [29]. Octafluoronaphthalene (OFN) crystal has one maximum emission ( em max ) at 353 nm, which is different from the one of 26NCA; thus 26NCA/OFN layer film is expected to present multicolor luminescence and even be used in soft optical device [29,41].…”

“…Moreover, it can solve the problem that low solubility will not be beneficial to the material's growth by solution process, such as 26NCA, and it provides a way to prepare light-emitting film materials which can be utilized in largescale flat panel display and soft optical device [29] by selecting appropriate substrate and photoactive materials. The work, herein, is based on LVPVDM to prepare singlecomponent metallic In film and organic 26NCA film and two-component films of 26NCA/In and 26NCA/OFN and study the fluorescence properties.…”

A stimuli-responsive double-stranded digold(i) helicate

“…One approach to 35 achieve various emission colours from the same compound is the existence of different crystalline and amorphous phases displaying different molecular conformations or packings. [6][7][8] Generally, the molecular packing is controlled by subtle interplay between different noncovalent intermolecular interactions among 40 the components, such as cations, anions, solvents, etc. Therefore, variations in noncovalent intermolecular interactions between the building blocks of a crystal could be an effective strategy to finetune its solid-state luminescent properties.…”

“…Therefore, variations in noncovalent intermolecular interactions between the building blocks of a crystal could be an effective strategy to finetune its solid-state luminescent properties. 8 Another strategy involves the controlling of molecular structures and/or packings 45 with external stimuli such as thermal, optical, electrical, mechanical, solvent vapour etc. leads to the development of stimuli-responsive luminescent materials whose emissions can be repeatedly switched between different emission colours.…”

“…leads to the development of stimuli-responsive luminescent materials whose emissions can be repeatedly switched between different emission colours. [1][2][3][4][5][6][7][8] Mechanochromic luminescent materials dynamically switch their 50 luminescence colour by responding to mechanical stimuli such as grinding, pressing or shearing. [1][2][3][4][5] The subsequent reversion to their original luminescence colour is usually achieved upon recrystallization or thermal treatment.…”