32
F. Ito
the DBDCS molecule and the long lifetime of its crystal, with nuclei of intermediate
lifetime, are observed. We show that the precipitation is slowed down by the presence
of a viscous skin at the interface between water and THF. From the analysis of the
decays, we map the concentrations of the three species with over half a million pixels
and show that nucleation and growth occur all along the device by the slow diffusion
of water into the THF inner flow.
A new method to synthesize and observe the precipitation of sub-micrometer
particles was optimized to study and control the early stage of microprecipitation.
The developed device is easy to construct and fully compatible with a wide range of
solvents. We used fluorescence lifetime imaging microscopy to detect not only the
oligomers of molecules that precede the formation of crystals but also the nucleation
and growth kinetics simultaneously.
There has been demand for a real-time, on-site, nondestructive, fluorescence
imaging technique to monitor the crystal formation and transformation processes of
organic fluorescent molecules. Hu and Tang et al. reported the fluorescent visualization of crystal formation and transformation processes of organic luminogens with
crystallization-induced emission characteristics [7]. In this work, (Z)-1-phenyl-2(3-phenylquinoxalin-2(1H)-ylidene)ethanone (PPQE) with crystallization-induced
emission properties was reported. Three polymorphs of PPQE with various emission behaviors were obtained with good reproducibility under controlled conditions
(Fig. 2.3). With the crystallization-induced emission characteristics and polymorphdependent luminescence of PPQE, a real-time, on-site, nondestructive fluorescence
imaging technique to monitor crystal transformation processes and crystal formation
from the amorphous state and dilute solution, respectively, was achieved. This study
provides a useful and convenient fluorescence tool for in situ crystal analysis, from
which detailed experimental evidence and mechanistic insights into crystal formation and transformation can be obtained through direct fluorescence visualization
with real-time, on-site, and nondestructive capabilities. It is a powerful and convenient tool for crystal analysis, providing detailed and valuable information about the
crystal formation and transformation processes.
2.3 Evaporative Crystallization of Mechanofluorochromic
Molecules
Dibenzoylmethanatoboron difluoride (BF 2 DBM) derivatives have excellent optical
properties, such as two-photon absorption cross sections [8, 9], high fluorescence
quantum yields in the solid state [10], multiple fluorescence colors [11–15], and
reversible mechanofluorochromic properties [16, 17]. In particular, BF 2 DBM based
on the 4-tert-butyl-4
-methoxydibenzoylmethane (avobenzone) boron difluoride
complex (BF 2 AVB) exhibits different emission depending on the crystal phase (polymorph) [18]. BF 2 AVB also has excellent fatigue resistance by photoirradiation and a
F. Ito
the DBDCS molecule and the long lifetime of its crystal, with nuclei of intermediate
lifetime, are observed. We show that the precipitation is slowed down by the presence
of a viscous skin at the interface between water and THF. From the analysis of the
decays, we map the concentrations of the three species with over half a million pixels
and show that nucleation and growth occur all along the device by the slow diffusion
of water into the THF inner flow.
A new method to synthesize and observe the precipitation of sub-micrometer
particles was optimized to study and control the early stage of microprecipitation.
The developed device is easy to construct and fully compatible with a wide range of
solvents. We used fluorescence lifetime imaging microscopy to detect not only the
oligomers of molecules that precede the formation of crystals but also the nucleation
and growth kinetics simultaneously.
There has been demand for a real-time, on-site, nondestructive, fluorescence
imaging technique to monitor the crystal formation and transformation processes of
organic fluorescent molecules. Hu and Tang et al. reported the fluorescent visualization of crystal formation and transformation processes of organic luminogens with
crystallization-induced emission characteristics [7]. In this work, (Z)-1-phenyl-2(3-phenylquinoxalin-2(1H)-ylidene)ethanone (PPQE) with crystallization-induced
emission properties was reported. Three polymorphs of PPQE with various emission behaviors were obtained with good reproducibility under controlled conditions
(Fig. 2.3). With the crystallization-induced emission characteristics and polymorphdependent luminescence of PPQE, a real-time, on-site, nondestructive fluorescence
imaging technique to monitor crystal transformation processes and crystal formation
from the amorphous state and dilute solution, respectively, was achieved. This study
provides a useful and convenient fluorescence tool for in situ crystal analysis, from
which detailed experimental evidence and mechanistic insights into crystal formation and transformation can be obtained through direct fluorescence visualization
with real-time, on-site, and nondestructive capabilities. It is a powerful and convenient tool for crystal analysis, providing detailed and valuable information about the
crystal formation and transformation processes.
2.3 Evaporative Crystallization of Mechanofluorochromic
Molecules
Dibenzoylmethanatoboron difluoride (BF 2 DBM) derivatives have excellent optical
properties, such as two-photon absorption cross sections [8, 9], high fluorescence
quantum yields in the solid state [10], multiple fluorescence colors [11–15], and
reversible mechanofluorochromic properties [16, 17]. In particular, BF 2 DBM based
on the 4-tert-butyl-4
-methoxydibenzoylmethane (avobenzone) boron difluoride
complex (BF 2 AVB) exhibits different emission depending on the crystal phase (polymorph) [18]. BF 2 AVB also has excellent fatigue resistance by photoirradiation and a