Mechanochromic and vapochromic fluorescence of a bulky π‐system: Alkyl chain‐length effects, triplex emission, and differential sensing of aniline vapors

Abstract

The interplay of mechanical grinding and aniline vapor fuming on the fluorescence of the pentiptycene-anthracene-pentiptycene π-conjugated molecules PAP-Cn, where n is 4, 8, 12, or 16 and refers to the number of carbon atom in the terminal alkyl chains, in solid films are reported. The differences and similarities among the four homologs have led to a conclusion of the formation of an emissive triplex state for the ground and fumed films. Thermogravimetric analysis reveals the guest-host molar ratio and the retention ability of the aniline on the various types of films. A stepwise protocol of fuming-grindingannealing is developed for fluorimetric differential sensing of eight substituted aniline vapors with a single probe of PAP-C8. The role of the bulky pentiptycene groups in the observed fluorescence properties is also discussed.

Porous Supramolecular Assembly of Pentiptycene-Containing Gold(I) Complexes: Persistent Excited-State Aurophilicity and Inclusion-Induced Emission Enhancement

“…The observed luminescence enhancement can be attributed to a shielding effect of the vapor molecules to molecular oxygen, a good phosphorescence quencher, because a similar or even larger extent of luminescence enhancement can be achieved by blowing nitrogen gas to 1 (Figure a). We then discovered that the vapor of pMDMA, a good electron donor, is able to induce not only a much higher intensity (300% enhancement) but also a color change from blue to cyan (λ max = 489 nm, Figure b) for the luminescence. The cyan luminescence profile remains upon sitting the pMDMA-fumed samples in the air, and the recovery of the initial status of 1 requires heating or vacuum (Figure S11), indicating a tighter binding of pMDMA in the pores of 1 , partly due to its higher boiling point ( T b = 198 °C).…”

“…We have recently demonstrated the utility of the bulky H-shaped pentiptycene scaffold in forming molecular solids of stimuli-responsive luminescence. − The three-dimensional pentiptycene scaffold is inherently more isotropic than a planar π-component in intermolecular nonbonded interactions. In addition, the U- and V-shaped cavities of the pentiptycene scaffold could accommodate nonspecific intermolecular π–π and C–H···π interactions.…”

Fluorescence sensor using porous host molecules deposited on filter paper with vapochromic and mechanochromic properties

“…More recently, numerous researchers have developed organic fluorescence reagents equipped with mechanochromism and vapochromism. 13–29 Recently, we reported that N , N ′-dipyrid-3-yl-1,4,5,8-naphthalenediimide (NDI) linked to two tris(pentafluorophenyl)borane (TPFB) ( 1 ) and N , N ′-bis(2-aminobenzophenone)-1,4,5,8-naphthalenetetracarboxylic diimide ( 2 ) formed 2 : 1 and 1 : 1 complexes, respectively, with toluene as single crystals with fluorescence based on the charge transfer interaction (Fig. 1).…”