Abstract
A new mechanoluminescent material (4-(diphenylamino)phenyl)(4-(diphenylphosphanyl)phenyl)methanone (CDpP), which displays tunable mechanoluminescent emission colors, has been designed and successfully synthesized. CDpP shows two distinct mechanoluminescent colors (blue and green) in different crystalline states. Single-crystal analyses and femtosecond transient emission studies reveal that the striking tunable mechanoluminescence properties of CDpP mainly originate from the different C-H···π interactions in the crystal structures. CDpP crystals with more C-H···π interactions show blue mechanoluminescence (ML), and the emission is attributed to the locally excited (LE)-state because the twisting process for the excited state is restricted by C-H···π interactions. Conversely, CDpP crystals with fewer C-H···π interactions display green ML, in which the red-shifted emission band originates from the twisted intramolecular charge transfer (TICT) excited state because the diphenylamine moiety is relatively free to rotate. The manipulation of weak intermolecular interactions in the crystalline state is a useful and reliable strategy for the tuning of the ML emission wavelengths.
Highlights
Organic light-emitting materials have attracted much attention in both academic and industrial arenas for many years.[1]
Internal molecular twisting processes have a signi cant impact on the intramolecular charge transfer (ICT) emissions.[15]
With different magnitudes of the twisting motions of the excited states, ICT emissions can be divided into two categories: locally excited (LE)-state emission and twisted intramolecular charge transfer (TICT) emissions.[15,16]
Summary
Organic light-emitting materials have attracted much attention in both academic and industrial arenas for many years.[1]. Internal molecular twisting processes have a signi cant impact on the intramolecular charge transfer (ICT) emissions.[15] With different magnitudes of the twisting motions of the excited states, ICT emissions can be divided into two categories: LE-state emission (excited states are not obviously twisted during their formation) and TICT emissions (excited states are twisted during their formation).[15,16] Tunable emission bands can be achieved by restricting or promoting the twisting processes by controlling the temperature, steric restrictions, and solvent polarity.[17] Lately, the processes involved in the solid-state TICT emission have been reported and well studied by Chujo and other groups and tunable emission was demonstrated by controlling the twisting processes in the solid states.[18] The TICT-based emission properties are related to intermolecular solid-state effects and, we presumed that the emission color might be switched by the manipulation of weak intermolecular interactions If this strategy can be realized in mechanoluminescent materials the emission properties can be controlled by tuning the intermolecular interactions, rather than chemical structure modi cation, allowing ease of control. We hope this study will provide a reliable strategy to tune the ML emission wavelengths by adjusting weak intermolecular interactions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
