47 research outputs found
Heterogeneity analysis of policy effect (city scale).
Heterogeneity analysis of policy effect (city scale).</p
The estimation results of the economic growth effect of municipal district for county (county-level city).
The estimation results of the economic growth effect of municipal district for county (county-level city).</p
Policy effect of municipal district for county (county-level city): Counterfactual test.
Policy effect of municipal district for county (county-level city): Counterfactual test.</p
Heterogeneity analysis of policy effect (city region).
Heterogeneity analysis of policy effect (city region).</p
Heterogeneity analysis of policy effect (development intensity of municipal districts).
Heterogeneity analysis of policy effect (development intensity of municipal districts).</p
Chirality Transfer from Polylactide to Achiral Fluorophore in Hierarchical Crystallization for Realizing Handedness-Tunable and Nonreciprocal Circularly Polarized Luminescence
Realizing chiral crystals from achiral compounds is an
important
but challenging issue. Here, a kebab-structured chiral supra-crystallization
complex is constructed in accomplishing hierarchical chiral crystallization
of achiral fluorescent compound (1,8-naphthalic anhydride, NA) employing
synthetic chiral macromolecules (polylactide, PLA) as a template.
Chirality transfer efficiently takes place from PLA to NA crystal
during the co-crystallization process, endowing the initial achiral
NA crystal with intense optical activity. More importantly, the obtained
chiral supra-crystals show remarkable circularly polarized luminescence
(CPL) properties, with the highest luminescence dissymmetric factor
up to 5 × 10–2. Moreover, handedness-tunable
and nonreciprocal CPL emissions are further realized in one single
sample by simply flipping and rotating the supra-crystallization composite
film, following a polarization mechanism. The work presents the first
polymer-based hierarchical chiral supra-crystal with switchable CPL
emissions and provides a simple and universal strategy for constructing
nonreciprocal CPL materials
Helical Polymer Working as a Chirality Amplifier to Generate and Modulate Multicolor Circularly Polarized Luminescence in Small Molecular Fluorophore/Polymer Composite Films
In-depth studies of chirality and circularly polarized
luminescence
(CPL) have become indispensable in the process of learning human nature.
Small molecules with CPL activity are one of the research hotspots.
However, the CPL properties of such materials are generally not satisfying.
Here, we synthesized a series of chiral small molecular fluorophores
that cannot demonstrate CPL emission themselves. By introducing an
optically inactive helical polymer, chirality transfer and chirality
amplification efficiently occur, thereby generating intense CPL emission.
Through combining different chiralized fluorophores, multicolor CPL-active
films with emission wavelength centered at 463, 525, and 556 nm were
fabricated, with the maximum luminescence dissymmetry factor (glum) being up to −0.028. Then, benefiting
from the strong CPL emission and appropriate energy donor–acceptor
system, we further established a circularly polarized fluorescence-energy
transfer (CPF-ET) strategy in which the CPL-active films work as a
donor emitting circularly polarized fluorescence to excite an achiral
fluorophore (Nile red) as the acceptor, producing red CPL with glum of up to −0.011 at around 605 nm