9 research outputs found
Guest-to-Host Transmission of Structural Changes for Stimuli-Responsive Adsorption Property
We show that structural changes of a guest molecule can
trigger
structural transformations of a crystalline host framework. Azobenzene
was introduced into a flexible porous coordination polymer (PCP),
and cis/trans isomerizations of the guest azobenzene by light or heat
successfully induced structural transformations of the host PCP in
a reversible fashion. This guest-to-host structural transmission resulted
in drastic changes in the gas adsorption property of the host鈥揼uest
composite, displaying a new strategy for creating stimuli-responsive
porous materials
Highly Photoconducting 蟺-Stacked Polymer Accommodated in Coordination Nanochannels
We report on the formation of single poly颅(<i>N</i>-vinylcarbazole)
(PVCz) chains in one-dimensional channels of [La颅(1,3,5-benzenetrisbenzoate)]<sub><i>n</i></sub>, where the side carbazolyl groups of the
confined PVCz are effectively 蟺-stacked. This ideal conformation
of PVCz chains in the coordination nanochannels contributed to a drastic
increase in hole mobility, which was 5 orders of magnitude higher
than that in the bulk state. It is also noteworthy that PVCz isolated
from the nanchannels still had a high hole mobility
Construction of a Hierarchical Architecture of Covalent Organic Frameworks via a Postsynthetic Approach
Covalent organic
frameworks (COFs) represent an emerging class
of crystalline porous materials that are constructed by the assembly
of organic building blocks linked via covalent bonds. Several strategies
have been developed for the construction of new COF structures; however,
a facile approach to fabricate hierarchical COF architectures with
controlled domain structures remains a significant challenge, and
has not yet been achieved. In this study, a dynamic covalent chemistry
(DCC)-based postsynthetic approach was employed at the solid鈥搇iquid
interface to construct such structures. Two-dimensional imine-bonded
COFs having different aromatic groups were prepared, and a homogeneously
mixed-linker structure and a heterogeneously core鈥搒hell hollow
structure were fabricated by controlling the reactivity of the postsynthetic
reactions. Solid-state nuclear magnetic resonance (NMR) spectroscopy
and transmission electron microscopy (TEM) confirmed the structures.
COFs prepared by a postsynthetic approach exhibit several functional
advantages compared with their parent phases. Their Brunauer鈥揈mmett鈥揟eller
(BET) surface areas are 2-fold greater than those of their parent
phases because of the higher crystallinity. In addition, the hydrophilicity
of the material and the stepwise adsorption isotherms of H<sub>2</sub>O vapor in the hierarchical frameworks were precisely controlled,
which was feasible because of the distribution of various domains
of the two COFs by controlling the postsynthetic reaction. The approach
opens new routes for constructing COF architectures with functionalities
that are not possible in a single phase
Photodynamic and Photothermal Effects of Semiconducting and Metallic-Enriched Single-Walled Carbon Nanotubes
Semiconducting and metallic single-walled carbon nanotubes
(s-SWNTs
and m-SWNTs) were enriched by agarose gel chromatography and their
photothermal and photodynamic effects were compared in H<sub>2</sub>O. Under near-infrared laser irradiation, s-SWNTs generated reactive
oxygen species (ROS) more than m-SWNTs, whereas m-SWNTs produced heat
more efficiently than s-SWNTs. More importantly, cancer cell killing
by PDE of s-SWNTs has been disclosed for the first time
Preparation of a Cross-Linked Porous Protein Crystal Containing Ru Carbonyl Complexes as a CO-Releasing Extracellular Scaffold
Protein crystals
generally are stable solid protein assemblies. Certain protein crystals
are suitable for use as nanovessels for immobilizing metal complexes.
Here we report the preparation of ruthenium carbonyl-incorporated
cross-linked hen egg white lysozyme crystals (<b>Ru路CL-HEWL</b>). <b>Ru路CL-HEWL</b> retains a Ru carbonyl moiety that
can release CO, although a composite of Ru carbonyl-HEWL dissolved
in buffer solution (<b>Ru路HEWL</b>) does not release CO.
We found that treatment of cells with <b>Ru路CL-HEWL</b> significantly increased nuclear factor kappa B (NF-魏B) activity
as a cellular response to CO. These results demonstrate that <b>Ru路CL-HEWL</b> has potential for use as an artificial extracellular
scaffold suitable for transport and release of a gas molecule
Modular Design of Domain Assembly in Porous Coordination Polymer Crystals via Reactivity-Directed Crystallization Process
The mesoscale design of domain assembly is crucial for
controlling
the bulk properties of solids. Herein, we propose a modular design
of domain assembly in porous coordination polymer crystals via exquisite
control of the kinetics of the crystal formation process. Employing
precursors of comparable chemical reactivity affords the preparation
of homogeneous solid-solution type crystals. Employing precursors
of distinct chemical reactivity affords the preparation of heterogeneous
phase separated crystals. We have utilized this reactivity-directed
crystallization process for the facile synthesis of mesoscale architecture
which are either solid-solution or phase-separated type crystals.
This approach can be also adapted to ternary phase-separated type
crystals from one-pot reaction. Phase-separated type frameworks possess
unique gas adsorption properties that are not observed in single-phasic
compounds. The results shed light on the importance of crystal formation
kinetics for control of mesoscale domains in order to create porous
solids with unique cooperative functionality
Modular Design of Domain Assembly in Porous Coordination Polymer Crystals via Reactivity-Directed Crystallization Process
The mesoscale design of domain assembly is crucial for
controlling
the bulk properties of solids. Herein, we propose a modular design
of domain assembly in porous coordination polymer crystals via exquisite
control of the kinetics of the crystal formation process. Employing
precursors of comparable chemical reactivity affords the preparation
of homogeneous solid-solution type crystals. Employing precursors
of distinct chemical reactivity affords the preparation of heterogeneous
phase separated crystals. We have utilized this reactivity-directed
crystallization process for the facile synthesis of mesoscale architecture
which are either solid-solution or phase-separated type crystals.
This approach can be also adapted to ternary phase-separated type
crystals from one-pot reaction. Phase-separated type frameworks possess
unique gas adsorption properties that are not observed in single-phasic
compounds. The results shed light on the importance of crystal formation
kinetics for control of mesoscale domains in order to create porous
solids with unique cooperative functionality
Fabrication of 蔚鈥慒e<sub>2</sub>N Catalytic Sites in Porous Carbons Derived from an Iron鈥揟riazolate Crystal
Fabrication
of 蔚鈥慒e<sub>2</sub>N Catalytic
Sites in Porous Carbons Derived from an Iron鈥揟riazolate Crysta
Integration of Porous Coordination Polymers and Gold Nanorods into Core鈥揝hell Mesoscopic Composites toward Light-Induced Molecular Release
Besides
conventional approaches for regulating in-coming molecules
for gas storage, separation, or molecular sensing, the control of
molecular release from the pores is a prerequisite for extending the
range of their application, such as drug delivery. Herein, we report
the fabrication of a new porous coordination polymer (PCP)-based composite
consisting of a gold nanorod (GNR) used as an optical switch and PCP
crystals for controlled molecular release using light irradiation
as an external trigger. The delicate core鈥搒hell structures
of this new platform, composed of an individual GNR core and an aluminum-based
PCP shell, were achieved by the selective deposition of an aluminum
precursor onto the surface of GNR followed by the replication of the
precursor into aluminum-based PCPs. The mesoscopic structure was characterized
by electron microscopy, energy dispersive X-ray elemental mapping,
and sorption experiments. Combination at the nanoscale of the high
storage capacity of PCPs with the photothermal properties of GNRs
resulted in the implementation of unique motion-induced molecular
release, triggered by the highly efficient conversion of optical energy
into heat that occurs when the GNRs are irradiated into their plasmon
band. Temporal control of the molecular release was demonstrated with
anthracene as a guest molecule and fluorescent probe by means of fluorescence
spectroscopy