TY - JOUR
T1 - Polymorphism and benzene solvent controlled stimuli responsive reversible fluorescence switching in triphenylphosphoniumfluorenylide crystals
AU - Hariharan, P. S.
AU - Baby Mariyatra, M.
AU - Mothi, E. M.
AU - Neels, Antonia
AU - Rosair, Georgina Margaret
AU - Anthony, Savarimuthu Philip
PY - 2017/6/7
Y1 - 2017/6/7
N2 - Triphenylphosphoniumfluorenylide (TPPFY), a fluorescent fluorene attached molecule, showed polymorphism and benzene solvent induced aggregation enhanced emission (AEE) in the solid state. Crystallization from CH3CN produced non-fluorescent crystals of TPPFY (TPPFY-1), whereas intense yellow fluorescent crystals (plates and blocks) were obtained from benzene (TPPFY-2, λmax = 538 nm, Φf = 38%). Structural analysis indicates that TPPFY-1 exhibits strong π⋯π interactions (3.371-3.399 Å) between fluorene units in the crystal lattice that quenched the solid state fluorescence. In contrast, the inclusion of a benzene molecule in TPPFY-2 prevents the close packing of fluorophores and shows intense yellow fluorescence in the solid state. TPPFY-2 showed only weak C-H⋯π interactions between fluorene and the phenyl group of triphenylphosphoniumylide. Hirshfeld surface analysis further supported the differences in the intermolecular interactions and molecular packing between TPPFY-1 and TPPFY-2. Interestingly, heating/strong crushing irreversibly converts fluorescent TPPFY-2 crystals to non-fluorescent TPPFY-1 crystals. However, recrystallization of TPPFY-1 from benzene produced fluorescent TPPFY-2 crystals. Thus TPPFY displays reversible off-on fluorescence switching heating/crushing and recrystallization. PXRD studies confirmed the polymorphism as well as the phase conversion of TPPFY-2 to TPPFY-1 by external stimuli. This study indicates the role of the benzene molecule in controlling the molecular packing and functional properties of TPPFY.
AB - Triphenylphosphoniumfluorenylide (TPPFY), a fluorescent fluorene attached molecule, showed polymorphism and benzene solvent induced aggregation enhanced emission (AEE) in the solid state. Crystallization from CH3CN produced non-fluorescent crystals of TPPFY (TPPFY-1), whereas intense yellow fluorescent crystals (plates and blocks) were obtained from benzene (TPPFY-2, λmax = 538 nm, Φf = 38%). Structural analysis indicates that TPPFY-1 exhibits strong π⋯π interactions (3.371-3.399 Å) between fluorene units in the crystal lattice that quenched the solid state fluorescence. In contrast, the inclusion of a benzene molecule in TPPFY-2 prevents the close packing of fluorophores and shows intense yellow fluorescence in the solid state. TPPFY-2 showed only weak C-H⋯π interactions between fluorene and the phenyl group of triphenylphosphoniumylide. Hirshfeld surface analysis further supported the differences in the intermolecular interactions and molecular packing between TPPFY-1 and TPPFY-2. Interestingly, heating/strong crushing irreversibly converts fluorescent TPPFY-2 crystals to non-fluorescent TPPFY-1 crystals. However, recrystallization of TPPFY-1 from benzene produced fluorescent TPPFY-2 crystals. Thus TPPFY displays reversible off-on fluorescence switching heating/crushing and recrystallization. PXRD studies confirmed the polymorphism as well as the phase conversion of TPPFY-2 to TPPFY-1 by external stimuli. This study indicates the role of the benzene molecule in controlling the molecular packing and functional properties of TPPFY.
UR - http://www.scopus.com/inward/record.url?scp=85021675261&partnerID=8YFLogxK
U2 - 10.1039/c7nj01136a
DO - 10.1039/c7nj01136a
M3 - Article
AN - SCOPUS:85021675261
SN - 1144-0546
VL - 41
SP - 4592
EP - 4598
JO - New Journal of Chemistry
JF - New Journal of Chemistry
IS - 11
ER -