Columnar Stacks Research Articles

Embryo movement is required for limb tendon maturation

IntroductionFollowing early cell specification and tenocyte differentiation at the sites of future tendons, very little is known about how tendon maturation into robust load-bearing tissue is regulated. Between embryonic day (E)16 and E18 in the chick, there is a rapid change in mechanical properties which is dependent on normal embryo movement. However, the tissue, cellular and molecular changes that contribute to this transition are not well defined.MethodsHere we profiled aspects of late tendon development (collagen fibre alignment, cell organisation and Yap pathway activity), describing changes that coincide with tissue maturation. We compared effects of rigid (constant static loading) and flaccid (no loading) immobilisation to gain insight into developmental steps influenced by mechanical cues.ResultsWe show that YAP signalling is active and responsive to movement in late tendon. Collagen fibre alignment increased over time and under static loading. Cells organise into end-to-end stacked columns with increased distance between adjacent columns, where collagen fibres are deposited; this organisation was lost following both types of immobilisation.DiscussionWe conclude that specific aspects of tendon maturation require controlled levels of dynamic muscle-generated stimulation. Such a developmental approach to understanding how tendons are constructed will inform future work to engineer improved tensile load-bearing tissues.

Rational Design of Fluorinated 2D Polymer Film Based on Donor-Accepter Architecture toward Multilevel Memory Device for Neuromorphic Computing.

Fluorine-containing 2D polymer (F-2DP) film is a desired system to regulate the charge transport in organic electronics but rather rarely reports due to the limited fluorine-containing building blocks and difficulties in synthesis. Herein, a novel polar molecule with antiparallel columnar stacking is synthesized and further embedded into an F-2DP system to control over the crystallinity of F-2DP film through self-complementary π-electronic forces. The donor-accepter-accepter'-donor' (D-A-A'-D') structure regulates the charge transportation efficiently, inducing multilevel memory behavior through stepwise charge capture and transfer processes. Thus, the device exhibits ternary memory behavior with low threshold voltage (Vth1 of 1.1V, Vth2 of 2.0V), clearly distinguishable resistance states (1:102:104) and ternary yield (83%). Furthermore, the stepwise formation of the charge complex endows the device with a wider range to regulate the conductive state, which allows its application in brain-inspired neuromorphic computing. Modified National Institute of Standards and Technology recognition can reach an accuracy of 86%, showing great potential in neuromorphic computing applications in the post-Moore era.

Semiconductive Potassium Hydroxamate Coordination Polymers with Dual Charge Transport Paths Originating from the π-π Stacking Columns.

Semiconductive coordination polymers (CPs) have recently garnered a significant amount of attention due to their widespread application in many areas. The "through-space" approach has emerged as the most versatile strategy for constructing semiconductive CPs. However, this approach often leads to the formation of unidirectional charge transport paths, resulting in anisotropic electrically conductive performance and low average conductivities in pressed pellets, thus presenting significant challenges for the practical application of semiconductive CPs. Consequently, there is a strong desire to explore simpler and more versatile strategies for designing semiconductive CPs with dual or multiple charge transport paths. Herein, we report on two semiconductive potassium hydroxamate coordination polymers, denoted as [K(HONDI)(H2O)2]n (1) and [K(HONDI)]n (2). Both compounds theoretically possess dual charge transport paths, occurring internally and externally within the π-π stacking columns of the ligands. Conductivity measurements revealed that compounds 1 and 2 both exhibit semiconductive properties, with their electrical conductivities reaching 2.3 × 10-6 and 1.9 × 10-7 S/cm, respectively, at 30 °C. Their electrically conductive performance could be attributed to theoretically biaxial "band-like" charge transport inside crystals and "hopping" charge transport between grain boundaries.

Supramolecular Assembly of Nitrogen-Containing Curved π-Conjugated Molecules to Polar Crystal

The chemistry of curved π-conjugated molecules has been extensively studied because of the development of their synthetic approach. Among the numerous studies, we have been engaged in nitrogen-containing curved π-conjugated molecules. These molecules have extended optical properties, redox-active behaviors, and electron-donating ability due to the electron-rich nature of nitrogen atoms. Recently, we have focused on the supramolecular assembling behavior of these compounds. For example, we have reported buckycatcher consisted of two azabuckybowls, providing two-photon absorbing host-guest complexes with fullerenes. In this presentation, we would like to show the packing behavior using π-extended azahelicenes and azabuckybowls. Our group has developed π-extended aza[5]helicene derivatives, showing brilliant emissive features. Recently, we succeeded in the synthesis of unsymmetrically substituted azahelicenes. We found that their stackings in the crystal were dependent on the substituent. X-ray diffraction analysis for all products showed π-stacked conformation with each other in the crystal (Figure 1b). In particular, azahelicenes with triisopropylsilyl groupswere found to align their dipole moments to form a one-dimensional columnar structure in the crystal. Polar crystals are expected to have applications in ferroelectric, piezoelectric, and nonlinear optical response materials. This is the first example of a polar crystal with helicenes, paving the way for novel piezoelectric organic materials.The second topic is related to azabuckybowl. In the crystal, azabuckybowl forms a face-to-face dimer by concave-convex interaction. In this study, we prepared two types of azabuckybowl perylene bisimide (PBI) dyads connected with alkyne linkages. PBIs have also been reported to show columnar stacking in solution. We anticipated that the segregate stacking should be achieved by recognizing the difference in structures between the bowl and planar geometry. The UV/vis absorption spectra revealed the presence of intramolecular charge-transfer interaction. In addition, the concentration-dependent absorption spectra and 1H NMR spectra indicated PBI and azabuckybowl units stacked with each other independently in solution (Figure 1a). Here, we would like to discuss about the effect of the effect of molecular shape on the supramolecular assembly with the data obtained using these compounds. Figure 1

Color Polymorphism and Room Temperature Phosphorescence of 4-Bromo-2,7-Di-Tert-Butyl- 9-Methoxypyrene.

Color polymorphism combined with crystal packing-dependent luminescence properties of polymorphs reflects differences in intermolecular interactions in different molecular arrangements. The title compound has two polymorphic crystal structures having strikingly different absorption and luminescence spectra that result from different packing motifs in the crystal lattice. The polymorph with brick wall-like packing of molecules is white and shows very weak violet fluorescence whereas the second polymorph, where molecules are arranged in columnar stacks, is bright yellow and displays intense green fluorescence with maximum at 487 nm (20530 cm-1). In the white polymorph, where the distance between neighboring chromophores is increased, absorption and fluorescence spectra are similar to those of monomer in solution, and intersystem crossing to triplet manifold is the dominant pathway of relaxation. In the yellow polymorph, molecules within the columnar stacks are rotated which mitigates the steric hindrance and leads to closer π-stacking of the pyrene cores. That increases the ππ overlap and strengthens intermolecular interactions decreasing energy of the excited states. This affects emission spectra and photophysical processes-fluorescence yield grows whereas triplet formation yield decreases when S1 is lowered below higher triplet states and conditions for effective vibronic spin-orbit coupling are not favorable. The effect is not observed for other similar pyrene derivatives, testifying the uniqueness of the phenomenon.

2-(Pyridin-4-yl)-2,3-di-hydro-1H-naphtho-[1,8-de][1,3,2]di-aza-borinine.

The title compound, C15H12BN3, is a type of di-aza-borinane featuring substitution at 1, 2, and 3 positions in the nitro-gen-boron six-membered heterocycle. It is comprised of two almost planar units, the pyridyl ring and the Bdan (dan = 1,8-di-aminona-phtho) group, which subtend a dihedral angle of 24.57 (5)°. In the crystal, the mol-ecules are linked into R 4 4(28) hydrogen-bonding networks around the fourfold inversion axis, giving cyclic tetra-mers. The mol-ecules form columnar stacks along the c axis.

Bidirectional π − π stacking for near-infrared photothermal effects and photo-thermo-electric conversion in a semiconductive hydroxamate coordination polymer

Photo-thermo-electric conversion is an emerging technology for utilizing solar energy. As the main component, photothermal materials play a significant role in achieving high conversion efficiency from sunlight to electrical energy. Organic photothermal materials have attracted intense attention recently due to their excellent photothermal efficiency and recycling capabilities. However, broad sunlight absorption in organics heavily relies on the realization of intramolecular or intermolecular charge transfer. Exploring more versatile and efficient methods to construct materials with broad sunlight absorption remains a great challenge. Herein, we report a novel photothermal compound from the perspective of modulating molecular assembly structure. By combining two distinct metal ions, Ba2+ and Mn2+, with the planar ligand H2ONDI, a new coordination polymer, {[BaMn(ONDI)2(H2O)3]⋅H2O}n (1), can be obtained. This coordination polymer exhibits rare bidirectional π−π stacking columns along both the a and b axis. The tightly bidirectional arrangement of ligands in 1 results in a broad optical absorption from the ultraviolet region to the near-infrared area, leading to intriguing near-infrared photothermal effects under irradiation of a laser of 808 nm with a efficiency of 42.3 %. By integrating with thermoelectric devices, 1 shows good application potential in the field of photo-thermo-electric conversion, with the maximum open circuit voltage reaching 313 mV under the irradiation of 1 sun. Furthermore, 1 displays semiconducting behavior because the presence of bidirectional π−π stacking columns facilitates charge transport along two directions, including hopping and band-like charge transport.

Vertical farming for lettuce production in limited space: a case study in Northern Thailand.

Greenhouse vertical farming under natural sunlight is an alternative farming technique that grows crops in a stacking column and extends in a vertical direction. Sunlight availability is one of the crucial factors for crop development in vertical farming. Therefore, this investigation aimed to examine the effect of sunlight availability on lettuce growth and yields at different levels of vertical shelves. Six shelves were constructed with three levels: upper, middle and lower levels. Lettuces (Lactuca sativa L.) as 'Baby Cos' and 'Green Oak' at 14 days after sowing were planted on the three levels. The photosynthetic photon flux density (PPFD) was recorded, and the PPFD values were then converted to the daily light integral (DLI). Plant height and canopy width were measured three times at 14, 21 and 28 days after transplanting. At maturity, fresh weight (FW) was directly monitored after harvest. The results showed that the highest PPFD and DLI values were found at the upper level (PPFD 697 μmol m-2 s-1 and DLI 29 mol m-2 d-1) in comparison to the middle (PPFD 391 μmol m-2 s-1 and DLI 16 mol m-2 d-1) and lower (PPFD 322 μmol m-2 s-1 and DLI 13 mol m-2 d-1) levels. The lowest plant height and canopy width values were observed on the upper levels for both lettuce varieties during the three measurement dates. The middle ('Baby Cos' = 123.8 g plant-1 and 'Green Oak' = 190.7 g plant-1) and lower ('Baby Cos' = 92.9 g plant-1 and 'Green Oak' = 203.7 g plant-1) levels had the higher values of FW in comparison to the upper level ('Baby Cos' = 84.5 g plant-1 and 'Green Oak' = 97.3 g plant-1). The values of light use efficiency (LUE) showed an increased trend from the upper to lower levels in both varieties, with values of 'Baby Cos' of 0.10 g mol-1 in the upper level, 0.28 g mol-1 in the middle level and 0.26 g mol-1 in the lower level and 'Green Oak' of 0.12 g mol-1 in the upper level, 0.44 g mol-1 in the middle level and 0.57 g mol-1 in the lower level. The findings of the study indicated the viability of utilizing vertical shelves for lettuce production.

Cholesterol-decorated porphyrin with circularly polarized luminescence: Design, synthesis and properties

Porphyrin was an excellent near-infrared dye but its rigid planar structure is not favorable for producing circularly polarized luminescence (CPL) property. Chirality transfer is an effective strategy to realize the CPL emission for achiral fluorescent unit. In this study, porphyrin derivatives with four cholesterol groups and dodecyl groups B4C and B4D were designed and synthesized. B4C and B4D exhibited good near-infrared emission in both solution and aggregated states. The solid film of B4C emitted strong left CPL fluorescence, while this CPL signal in mesomorphic film was stronger and switched to right CPL emission. The fluorescence dissymmetry factor (glum) of B4C was as high as 2.31×10−2. These results suggested the effective chirality transfer from cholesterol units to porphyrin units based on spiral columnar liquid crystalline stacking and the CPL signal of B4C was tunable by temperature, supplying a good way on design and synthesis of CPL material with tunable CPL signal based on achiral dyes.

Synthesis, structure, and properties of a bay-fluorinated triphenylene

Abstract The synthesis, structure, and electronic properties of a bay-fluorinated triphenylene are reported. 2,3,6,7,10,11-Hexaethoxy-1,4,5,8,9,12-hexafluorotriphenylene (1) was synthesized via the 6-fold deprotonation and electrophilic fluorination of hexaethoxytriphenylene (2). X-ray crystallography revealed a distorted structure and columnar stacking for 1. The steric and electronic properties of 1 were examined by using photophysical measurements and theoretical calculations.

Radical Cation Salts of Hetera‐Buckybowls: Polar Crystals, Negative Thermal Expansion and Phase Transition

AbstractRadical cation salts of π‐conjugated polycycles are rich in physical properties. Herein, two kinds of hetera‐buckybowls, ethoxy‐substituted trithiasumanene (3SEt) and triselenasumanene (3SeEt), are synthesized as electron donors. Galvanostatic oxidation of them affords radical cation salts (3SEt)5(TTFMPB)3, (3SeEt)5(TTFMPB)3, (3SEt)4PMA, and (3SeEt)4PMA, where PMA is Keggin‐type phosphomolybdate and TTFMPB is tetrakis[3,5‐bis(trifluoromethyl)‐phenyl]borate. In these salts, 3SEt/3SeEt are partially charged and show distinct conformation change with the site charge and counter anions. In TTFMPB salts, (TTFMPB)− forms hexagonal channels that accommodate the packing columns of 3SEt/3SeEt. In particular, (3SEt)5(TTFMPB)3 adopts the R3c space group and is a polar crystal with the columns of 3SEt all in the up‐bowl direction. The PMA salts of 3SEt/3SeEt are polar crystals (C2 space group) with 3SEt/3SeEt being planar and forming columnar stacks. (3SeEt)4PMA shows a structural modulation below 200 K, namely, negative thermal expansion (NTE) of the unit cell volume and enlargement of the intermolecular distances between neighboring 3SeEt molecules. The four salts are semiconductors with an activation energy of 0.18–0.38 eV. The conductivity of (3SeEt)4PMA shows a reversible transition upon cooling and heating, in accordance to the NTE structural modulation. This work paves the way toward conducting materials based on hetera‐buckybowls.

Radical Cation Salts of Hetera-Buckybowls: Polar Crystals, Negative Thermal Expansion and Phase Transition.

Radical cation salts of π-conjugated polycycles are rich in physical properties. Herein, two kinds of hetera-buckybowls, ethoxy-substituted trithiasumanene (3SEt) and triselenasumanene (3SeEt), are synthesized as electron donors. Galvanostatic oxidation of them affords radical cation salts (3SEt)5 (TTFMPB)3 , (3SeEt)5 (TTFMPB)3 , (3SEt)4 PMA, and (3SeEt)4 PMA, where PMA is Keggin-type phosphomolybdate and TTFMPB is tetrakis[3,5-bis(trifluoromethyl)-phenyl]borate. In these salts, 3SEt/3SeEt are partially charged and show distinct conformation change with the site charge and counter anions. In TTFMPB salts, (TTFMPB)- forms hexagonal channels that accommodate the packing columns of 3SEt/3SeEt. In particular, (3SEt)5 (TTFMPB)3 adopts the R3c space group and is a polar crystal with the columns of 3SEt all in the up-bowl direction. The PMA salts of 3SEt/3SeEt are polar crystals (C2 space group) with 3SEt/3SeEt being planar and forming columnar stacks. (3SeEt)4 PMA shows a structural modulation below 200 K, namely, negative thermal expansion (NTE) of the unit cell volume and enlargement of the intermolecular distances between neighboring 3SeEt molecules. The four salts are semiconductors with an activation energy of 0.18-0.38 eV. The conductivity of (3SeEt)4 PMA shows a reversible transition upon cooling and heating, in accordance to the NTE structural modulation. This work paves the way toward conducting materials based on hetera-buckybowls.

Multistate structures in a hydrogen-bonded polycatenation non-covalent organic framework with diverse resistive switching behaviors

The inherent structural flexibility and reversibility of non-covalent organic frameworks have enabled them to exhibit switchable multistate structures under external stimuli, providing great potential in the field of resistive switching (RS), but not well explored yet. Herein, we report the 0D+1D hydrogen-bonded polycatenation non-covalent organic framework (HOF-FJU-52), exhibiting diverse and reversible RS behaviors with the high performance. Triggered by the external stimulus of electrical field E at room temperature, HOF-FJU-52 has excellent resistive random-access memory (RRAM) behaviors, comparable to the state-of-the-art materials. When cooling down below 200 K, it was transferred to write-once-read-many-times memory (WORM) behaviors. The two memory behaviors exhibit reversibility on a single crystal device through the temperature changes. The RS mechanism of this non-covalent organic framework has been deciphered at the atomic level by the detailed single-crystal X-ray diffraction analyses, demonstrating that the structural dual-flexibility both in the asymmetric hydrogen bonded dimers within the 0D loops and in the infinite π–π stacking column between the loops and chains contribute to reversible structure transformations between multi-states and thus to its dual RS behaviors.

Perylene with peripherally fused pyrrole and pyridine: columnar packing, anti-Kasha dual emission and reactive oxygen species generation

With a spatially separated donor–acceptor group within a plane, PerNN and its derivatives demonstrate properties such as columnar stacking, anti-Kasha dual emission responsive to solvent polarity and efficient ROS generation.

Electron transport chain-inspired coordination polymers for macroscopic spatiotemporal scales of charge separation and transport in photocatalysis.

Classic homogeneous photocatalysis is limited by the temporal transience and the spatial proximity of photoinduced charge separation and transport. The electron transfer chain (ETC) in cellular respiration can mediate unidirectional and long-range electron transfer to isolate the oxidation and reduction centres. Inspired by this, we modified electron-accepting (A) viologen with π-extending thiazolothiazole and electron-donating (D) phenyl carboxylate into a D-A-π-A-D-type ligand and assembled segregated dye stacking in coordination polymer Cd-TzBDP for breaking the spatiotemporal limitation of single-molecule photocatalysis. The offset characteristics of D-A segregated stacking not only allowed the photoinduced-2e- transfer from the D-type carboxylate terminal to the spatially adjacent A-type viologen motif within 1 ps but also permitted the following delocalization of e- and h+ along stacked columns. These advantages endowed Cd-TzBDP with long-lived photochromic visualization of intermittent aerobic photooxidation steps, which enabled the bioinspired ETC-mediated aerobic respiration of mitochondria, achieving the continuous photocatalytic α-C(sp3)-H functionalization of tertiary amines with pharmaceutical interest. Enlightened by ETC-mediated electron leak in hypoxia, the coordination polymer was further employed in a photocatalytic membrane reactor, which visually illustrated the photo-driven cross-membrane long-range transfers of multiple electrons and protons from the hypoxic compartment to normoxic one, benefiting the distal photooxidation and photoreduction with biomimetic compartment selectivity.

Core charge of imidazolium annulated triphenylene derivatives induces discotic columnar mesomorphism.

Thermotropic ionic liquid crystals have remained a relatively little studied group of materials despite their many potential applications as anisotropic ionic liquids and charge (ion and electron/hole) transporting materials. Particularly rare are core charged discotic liquid crystals because their synthesis is usually more involved, and their molecular design is less established. Presented here is a straightforward and versatile synthetic approach to imidazolium annulated triphenylene derivatives. Their neutral imidazole precursors are not liquid crystalline while the imidazolium salts display hexagonal discotic columnar mesophases over a wide range of temperatures and as low as 47 °C. Computational studies at the DFT and PM6 levels of theory confirmed much higher stacking energies for the imidazolium salts compared to the neutral imidazole precursors. They also predicted the anions of columnar stacks of imidazolium salts to be positioned in the bay-positions next to the imidazolium unit and in-plane with the polyaromatic system. The anions were stabilized in the bay position by multiple interactions with partially positively charged H atoms and do not interfere with π-π stacking.

Spin and dielectric transitions promoted by dimerization of anionic radical stacks and volume-conserving motion of cations in an ion-pair compound.

Demonstrating the mechanism of a structural phase transition (SPT) is significantly important for guiding the precise design of new phase transition materials. Herein, an ion-pair compound [DPIm][Ni(mnt)2] (1, DPIm+ = 1,3-dipropylimidazolium and mnt2- = maleonitriledithiolate) has been obtained and thoroughly characterized through microanalysis, spectral, and thermal analysis techniques. The [Ni(mnt)2]- anions form columnar stacks, featuring one-dimensional (1D) S = ½ spin chains. 1 undergoes an SPT, associated with thermal, magnetic, and dielectric anomalies. The SPT results from the competition between antiferromagnetic (AFM) coupling interactions within anion stacks and elastic deformation of the lattice. The magnetic anomaly arises from changes in the magnetic coupling constant within an anion stack between two phases, while the dielectric anomaly is due to the volume-conserving motion of the imidazolyl ring in the cation. 1 exhibits high-κ characteristics, attributed to the electron polarization of both anions and cations, ion displacement, and dipole orientation polarization of cations. It is also demonstrated that a longer dialkyl chain inhibits the rotational freedom of the imidazolyl ring, resulting in the absence of a plastic crystal state in 1 compared to others containing [Ni(mnt)2]- and dialkylimidazolium.

Ultralow thermal conductivity and thermally-deactivated electrical transport in a 1D silver array with alternating δ-bonds.

We report the synthesis of a (TMA)AgBr2 (TMA = tetramethylammonium) crystal, which comprises inorganic anionic chains of -(AgBr2)∝- stabilized by columnar stacks of organic TMA cations with a periodic arrangement of shorter and longer Ag(i)⋯Ag(i) bonds, even though all the Ag(i) ions are chemically equivalent. The presence of two chemically non-equivalent bridging Br ions is attributed to the primary cause of such an unusual arrangement, as clearly visualized in the charge density plot of (TMA)AgBr2 extracted from the theoretical calculations based on density functional theory. Remarkably, we identified from the orbital-projected density of states the existence of alternate δ-like bonding involving d xy orbitals of 4d10 Ag(i), which was attributed to the cause for ultralow thermal conductivity and thermally-deactivated electrical transport in (TMA)AgBr2. Barring the energetics, our observations on the existence of a δ-bond will shed new light in understanding the nature of metal-metal chemical bonding and its unprecedented implications.

Effects of π-π Stacking on Shale Gas Adsorption and Transport in Nanopores.

The π-π interaction is a prevalent driving force in the formation of various organic porous media, including the shale matrix. The configuration of π-π stacking in the shale matrix significantly influences the properties of shale gas and plays a crucial role in understanding and exploiting gas resources. In this research, we investigate the impact of different π-π stacking configurations on the adsorption and transport of shale gas within the nanopores of the shale matrix. To achieve this, we construct kerogen nanopores using π-π stacked columns with varying stacking configurations, such as offset/parallel stacking types and different orientations of the stacked columns. Through molecular dynamics simulations, we examined the adsorption and transport of methane within these nanopores. Our findings reveal that methane exhibits stronger adsorption in smoother nanopores, with this adsorption remaining unaffected by the nanoflow. We observe a heterogeneous distribution of the 2D adsorption free energy, which correlates with the specific π-π stacking configurations. Additionally, we introduce the concept of "directional roughness" to describe the surface characteristics, finding that the nanoflow flux increases as the roughness decreases. This research contributes to the understanding of shale gas behavior in the shale matrix and provides insights into nanoflow properties in other porous materials containing π-π stackings.

Two-Dimensional Supramolecular Polymerization of a Bis-Urea Macrocycle into a Brick-Like Hydrogen-Bonded Network.

We report on a dendronized bis-urea macrocycle 1 self-assembling via a cooperative mechanism into two-dimensional (2D) nanosheets formed solely by alternated urea-urea hydrogen bonding interactions. The pure macrocycle self-assembles in bulk into one-dimensional liquid-crystalline columnar phases. In contrast, its self-assembly mode drastically changes in CHCl3 or tetrachloroethane, leading to 2D hydrogen-bonded networks. Theoretical calculations, complemented by previously reported crystalline structures, indicate that the 2D assembly is formed by a brick-like hydrogen bonding pattern between bis-urea macrocycles. This assembly is promoted by the swelling of the trisdodecyloxyphenyl groups upon solvation, which frustrates, due to steric effects, the formation of the thermodynamically more stable columnar macrocycle stacks. This work proposes a new design strategy to access 2D supramolecular polymers by means of a single non-covalent interaction motif, which is of great interest for materials development.