Provided is a solid luminescent quinoline compound capable of emitting light in a crystalline state, capable of changing the luminescent color not requiring modification of molecular configuration and capable of emitting light in response to external pressure such as heat, physical pressure, etc. The quinoline compound is represented by the following general formula (1):
wherein R
1
may be the same or different, each representing any of CF
3
or CF
3
CF
2
; R
2
represents any of an amino group, an N,N-dimethylamino group, an N-phenylamino group, a carbazole group, an N-methylamino group or an N-methyl-N-phenylamino group.
The alkylmorpholine group is well-known to favor accumulation in lysosomes, but the TFMAQ derivatives containing ethylmorpholine groups only showed limited accumulation in lysosomes and, instead, preferential accumulation in lipid droplets.
An optical pH probe is a simple and effective tool for determining an accurate pH value in its localized area. However, basic pH probes with pKBH+ values above 8 have rarely been reported, although many components with high pKa such as arginine play important roles in vivo. Herein, we introduce novel colorimetric and fluorescent basic probes 1–5, which are designed using push–pull-type aminoquinoline and aminobenzoquinoline fluorophores, with pKBH+ values ranging from 8.4 to 9.9. After the basicity of the remarkably sensitive basic probe 4 was tuned, it was able to successfully distinguish between the pKa values of MeOH (15.5) and EtOH (15.9), thus displaying selective protonation and fluorescence enhancement in MeOH over EtOH. Our pH probes can be used to detect MeOH poisoning in commercial EtOH products such as hand sanitizers, providing an effective solution to this problem observed during the COVID-19 pandemic.