17 research outputs found
Soft chromophore featured liquid porphyrins and their utilization toward liquid electret applications
Optoelectronically active viscous liquids are ideal for fabricating foldable/stretchable electronics owing to their excellent deformability and predictable Ď-unit-based optoelectronic functions, which are independent of the device shape and geometry. Here we show, unprecedented 'liquid electret' devices that exhibit mechanoelectrical and electroacoustic functions, as well as stretchability, have been prepared using solvent-free liquid porphyrins. The fluidic nature of the free-base alkylated-tetraphenylporphyrins was controlled by attaching flexible and bulky branched alkyl chains at different positions. Furthermore, a subtle porphyrin ring distortion that originated from the bulkiness of alkyl chains was observed. Its consequences on the electronic perturbation of the porphyrin-unit were precisely elucidated by spectroscopic techniques and theoretical modelling. This molecular design allows shielding of the porphyrin unit by insulating alkyl chains, which facilitates its corona-charged state for a long period under ambient conditions
Dissimilarity Between Heat and Momentum Transfer of Turbulent Heat Transfer over Surfaces with Hemisphere Protrusions
AlkylâĎ Functional Molecular Gels: Control of Elastic Modulus and Improvement of Electret Performance
The development of optoelectronically-active soft materials is drawing attention to the application of soft electronics. A room-temperature solvent-free liquid obtained by modifying a Ď-conjugated moiety with flexible yet bulky alkyl chains is a promising functional soft material. Tuning the elastic modulus (Gâ˛) is essential for employing optoelectronically-active alkylâĎ liquids in deformable devices. However, the range of GⲠachieved through the molecular design of alkylâĎ liquids is limited. We report herein a method for controlling GⲠof alkylâĎ liquids by gelation. Adding 1 wt% low-molecular-weight gelator formed the alkylâĎ functional molecular gel (FMG) and increased GⲠof alkylâĎ liquids by up to seven orders of magnitude while retaining the optical properties. Because alkylâĎ FMGs have functional Ď-moieties in the gel medium, this new class of gels has a much higher content of Ď-moieties of up to 59 wt% compared to conventional Ď-gels of only a few wt%. More importantly, the gel state has a 23% higher charge-retention capacity than the liquid, providing better performance in deformable mechanoelectric generator-electret devices. The strategy used in this study is a novel approach for developing next-generation optoelectronically-active FMG materials
Investigation of the Fabrication Parameters Affecting the Cathodoluminescence Property of ZnAl2O4:Mn Green Phosphors
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Quest for a Rational Molecular Design of AlkylâDistyrylbenzene Liquid by Substitution Pattern Modulation
Alkyl-Ď functional molecular liquids (FMLs) are of interest for fabricating soft electronic devices due to their fluidic nature and innate optoelectronic functions from the Ď-conjugated moiety. However, predictable development of alkyl-Ď FMLs with the desired liquid and optoelectronic properties is challenging. A series of alkylâdistyrylbenzene (DSB) liquids was studied in terms of the substituent position effect by attaching 2-octyldodecyl chains at (2,4-), (2,5-), (2,6-), and (3,5-). The effect of the alkyl chain length was investigated by attaching 2-hexyldecyl, 2-decyltetradecyl (C10C14), and 2-dodecylhexadecyl at the (2,5-) substituent position. The 2,5-C10C14 substituent pattern constructed a superior alkylâDSB liquid with a lower viscosity, intrinsic optical properties, and high thermal- and photo-stabilities. The discovered 2,5-C10C14 was applied to dicyanostyrylbenzene and comparable liquid physical and optical superiorities were confirmed. This molecular design is useful for creating alkyl-Ď FMLs with the aforementioned advantages, which are applicable for deformable and flowable optoelectronic devices
Thermo-/mechano-chromic Chiral Coordination Dimer: Formation of Switchable and Metastable Discrete Structure through Chiral Self-sorting
Although strong chiral self-sorting (e.g., sergeants and soldiers principle, majority rules) often emerges in extended covalent or supramolecular polymers, the phenomenon is generally weak in discrete assemblies (e.g., dimers, oligomers) of small molecules due to the lack of a cooperative growth mechanism. Consequently, chiral self-sorting has been overlooked in the design of switchable and metastable discrete supramolecular structures. Here we report a benzo[h]quinoline-based iridi-um(III) complex (Ir) with helical chirality at its metal centre, which forms preferentially a homochiral dimer and exhibits thermo-/mechano-chromism based on a monomer-dimer transformation. While a five-coordinate monomer is formed in ra-cemic or enantiopure Ir solution at 25 °C, a six-coordinate homochiral dimer complex is formed almost exclusively at low temperatures, with a higher degree of dimerization in enantiopure Ir solution. Estimation of dimerization binding constants (K) and thermodynamic parameters (ÎH and ÎS) based on variable temperature UV-Vis and 1H NMR spectra reveal a strong preference for homochiral dimerization (largest known value for coordination complex, Khomo/Khetero > 50) as a result of steric repulsions of peripheral alkyl chains in Ir heterochiral dimers. Notably, crystals of homochiral dimer are metastable, under-going a distinct colour change upon grinding (from yellow to red) due to mechanical cleavage of coordination bonds (i.e., a dimer to monomer transformation). Ir dimerization involves both strong homochiral self-sorting preference and connected thermo-/mechano-chromic behaviour, leading to emergence of dynamic functionality based on the rational design of discrete chiral assemblies
Distinct Responses to Mechanical Grinding and Hydrostatic Pressure in Luminescent Chromism of Tetrathiazolylthiophene
Luminescent
mechanochromism has been intensively studied in the
past few years. However, the difference in the anisotropic grinding
and the isotropic compression is not clearly distinguished in many
cases, in spite of the importance of this discrimination for the application
of such mechanochromic materials. We now report the distinct luminescent
responses of a new organic fluorophore, tetrathiazolylthiophene, to
these stresses. The multichromism is achieved over the entire visible
region using the single fluorophore. The different mechanisms of a
blue shift by grinding crystals and of a red shift under hydrostatic
pressure are fully investigated, which includes a high-pressure single-crystal
X-ray diffraction analysis. The anisotropic and isotropic modes of
mechanical loading suppress and enhance the excimer formation, respectively,
in the 3D hydrogen-bond network
Thermo-/Mechano-Chromic Chiral Coordination Dimer: Formation of Switchable and Metastable Discrete Structure through Chiral Self-Sorting
Although strong chiral self-sorting often emerges in
extended covalent
or supramolecular polymers, the phenomenon is generally weak in discrete
assemblies (e.g., dimers and oligomers) of small molecules due to
the lack of a cooperative growth mechanism. Consequently, chiral self-sorting
has been overlooked in the design of switchable and metastable discrete
supramolecular structures. Here, we report a butyl-benzo[h]quinoline-based iridium(III) complex (Bu-Ir) with helical
chirality at its metal center, which forms preferentially a homochiral
dimer and exhibits thermo-/mechano-chromism based on a monomerâdimer
transformation. While a five-coordinate monomer is formed in a racemic
or an enantiopure Bu-Ir solution at 25 °C, a six-coordinate
homochiral dimer complex is formed almost exclusively at low temperatures,
with a higher degree of dimerization in enantiopure Bu-Ir solution. Estimation of apparent dimerization binding constants
(K) and thermodynamic parameters (ÎH and ÎS) based on variable temperature
ultravioletâvisible (UVâvis) and 1H NMR spectra
reveals a strong preference for homochiral dimerization (largest known
value for the coordination complex, Khomo/Khetero > 50). Notably, crystals
of
the homochiral dimer are metastable, undergoing a distinct color change
upon grinding (from yellow to red) due to mechanical cleavage of coordination
bonds (i.e., a dimer to monomer transformation). A comparison with
control compounds having different substituents (proton, methyl, isopropyl,
and phenyl groups) reveals that Bu-Ir dimerization involves
both strong homochiral self-sorting preference and connected thermo-/mechano-chromic
behavior, which is based on matched propeller-shaped chirality and
subtle steric repulsion between alkyl substituents that render the
homochiral dimer switchable and metastable. These findings provide
substantial insights into the emergence of dynamic functionality based
on the rational design of discrete chiral assemblies
Thermo-/Mechano-Chromic Chiral Coordination Dimer: Formation of Switchable and Metastable Discrete Structure through Chiral Self-Sorting
Although strong chiral self-sorting often emerges in
extended covalent
or supramolecular polymers, the phenomenon is generally weak in discrete
assemblies (e.g., dimers and oligomers) of small molecules due to
the lack of a cooperative growth mechanism. Consequently, chiral self-sorting
has been overlooked in the design of switchable and metastable discrete
supramolecular structures. Here, we report a butyl-benzo[h]quinoline-based iridium(III) complex (Bu-Ir) with helical
chirality at its metal center, which forms preferentially a homochiral
dimer and exhibits thermo-/mechano-chromism based on a monomerâdimer
transformation. While a five-coordinate monomer is formed in a racemic
or an enantiopure Bu-Ir solution at 25 °C, a six-coordinate
homochiral dimer complex is formed almost exclusively at low temperatures,
with a higher degree of dimerization in enantiopure Bu-Ir solution. Estimation of apparent dimerization binding constants
(K) and thermodynamic parameters (ÎH and ÎS) based on variable temperature
ultravioletâvisible (UVâvis) and 1H NMR spectra
reveals a strong preference for homochiral dimerization (largest known
value for the coordination complex, Khomo/Khetero > 50). Notably, crystals
of
the homochiral dimer are metastable, undergoing a distinct color change
upon grinding (from yellow to red) due to mechanical cleavage of coordination
bonds (i.e., a dimer to monomer transformation). A comparison with
control compounds having different substituents (proton, methyl, isopropyl,
and phenyl groups) reveals that Bu-Ir dimerization involves
both strong homochiral self-sorting preference and connected thermo-/mechano-chromic
behavior, which is based on matched propeller-shaped chirality and
subtle steric repulsion between alkyl substituents that render the
homochiral dimer switchable and metastable. These findings provide
substantial insights into the emergence of dynamic functionality based
on the rational design of discrete chiral assemblies
Thermo-/Mechano-Chromic Chiral Coordination Dimer: Formation of Switchable and Metastable Discrete Structure through Chiral Self-Sorting
Although strong chiral self-sorting often emerges in
extended covalent
or supramolecular polymers, the phenomenon is generally weak in discrete
assemblies (e.g., dimers and oligomers) of small molecules due to
the lack of a cooperative growth mechanism. Consequently, chiral self-sorting
has been overlooked in the design of switchable and metastable discrete
supramolecular structures. Here, we report a butyl-benzo[h]quinoline-based iridium(III) complex (Bu-Ir) with helical
chirality at its metal center, which forms preferentially a homochiral
dimer and exhibits thermo-/mechano-chromism based on a monomerâdimer
transformation. While a five-coordinate monomer is formed in a racemic
or an enantiopure Bu-Ir solution at 25 °C, a six-coordinate
homochiral dimer complex is formed almost exclusively at low temperatures,
with a higher degree of dimerization in enantiopure Bu-Ir solution. Estimation of apparent dimerization binding constants
(K) and thermodynamic parameters (ÎH and ÎS) based on variable temperature
ultravioletâvisible (UVâvis) and 1H NMR spectra
reveals a strong preference for homochiral dimerization (largest known
value for the coordination complex, Khomo/Khetero > 50). Notably, crystals
of
the homochiral dimer are metastable, undergoing a distinct color change
upon grinding (from yellow to red) due to mechanical cleavage of coordination
bonds (i.e., a dimer to monomer transformation). A comparison with
control compounds having different substituents (proton, methyl, isopropyl,
and phenyl groups) reveals that Bu-Ir dimerization involves
both strong homochiral self-sorting preference and connected thermo-/mechano-chromic
behavior, which is based on matched propeller-shaped chirality and
subtle steric repulsion between alkyl substituents that render the
homochiral dimer switchable and metastable. These findings provide
substantial insights into the emergence of dynamic functionality based
on the rational design of discrete chiral assemblies