Crystalline Packing Research Articles

Impact of Irreversible Adsorption on Molecular Ordering and Charge Transport in Poly(3-hexylthiophene) Thin Films on Solid Substrates.

We investigate the irreversible adsorption of poly(3-hexylthiophene) (P3HT) polymer thin films on silicon dioxide/silicon (SiO2/Si) substrates during thermal annealing at a temperature below the melting temperature (Tm) but far above the glass transition temperature (Tg), i.e., Tg ≪ T = 170 °C < Tm, and its effect on their crystalline ordering and charge transport properties. It was found that short-time annealing enhances the molecular ordering of P3HT films, while prolonged thermal annealing gradually disrupts the crystalline structures and reduces the overall crystallinity of the film. Concurrently, thermal annealing at this temperature facilitates the slow irreversible adsorption of P3HT chains at the polymer-solid interface, resulting in the formation of a 1.7 Rg-thick (∼18 nm thick) adsorbed layer on SiO2/Si substrates that is fully amorphous and contains a large fraction of loosely adsorbed chains. We postulate that such irreversible adsorption is responsible for the reduced crystalline packing of P3HT at the polymer-solid interface at Tg ≪ T < Tm, which further disrupts the molecular ordering of the entire 46 nm thick P3HT film by a long-range perturbation effect. Electrical measurements using an organic field-effect transistor (OFET) device reveal that the enhanced charge carrier mobility of P3HT films correlates with an optimized annealing time at Tg ≪ T < Tm, which achieves a balance between maximizing molecular ordering and minimizing the impact of irreversible chain adsorption. These findings provide new insights into the underlying mechanism of thermal annealing in tailoring the structure and property of conjugated polymer thin films prepared on solid substrates.

Structural elucidation of the dichloridodioxido-[(4,7-dimethyl)-1,10-phenanthroline]molybdenum(VI) (C14H12Cl2MoN2O2)

In this work, the synthesis, characterization, and X-ray powder diffraction data for dichloridodioxido-[(4,7-dimethyl)-1,10-phenanthroline]molybdenum(VI) are reported. The crystal structure of this compound was solved from powder diffraction data using the simulated annealing method with a subsequent refinement using the Rietveld method. The dioxo-molybdenum (VI) complex C14H12Cl2MoN2O2 crystallizes in a monoclinic system with space group C2/c (N° 15) with refined unit-cell parameters a = 12.9495 (5) Å, b = 9.7752 (4) Å,c = 12.0069 (6) Å, β = 101.702 (3) °, unit-cell volume V = 1488.27 (11) Å3, and values of Z′ = 0.5 and Z = 4. The molecules are organized into chains diagonally along the a and c axis. Parallel polyhedra are observed along these axes formed by the interactions of Mo, Cl, O, and N atoms present in the coordination sphere. The crystalline packing of this dioxo-molybdenum (VI) complex is dominated by five intermolecular hydrogen bonds, two intramolecular hydrogen bonds, and the four interactions between the centroids (CgI⋯CgJ) of the aromatic rings. An analysis of the Hirshfeld surface revealed that the greatest contributions of the attractive forces are given by H⋯Cl/Cl⋯H, H⋯C/C⋯H, H⋯O/O⋯H, and H⋯H interactions.

Achieving Efficient Intrinsically Stretchable Organic Photovoltaics with a Conjugated and Elastomeric Dual‐Network Morphology

AbstractStretchable organic photovoltaics (OPVs) are pivotal for advancing conformable electronics, yet achieving both efficient and intrinsically stretchable OPVs remains a significant challenge. The main issue is maintaining electronic and mechanical properties under deformation. Here, a ternary blend system, PTzBI‐oF:PYIT:EVA is presented, incorporating ethylene‐vinyl acetate (EVA) to establish a conjugated and elastomeric dual‐network morphology. The elastomer network dissipates applied stress, preserving the crystalline packing of the conjugated network and enabling improved mechanical stability of charge carrier generation and transport. Specifically, with 15% EVA content, the ternary blend achieved a power conversion efficiency (PCE) of 15.28% in rigid devices and exhibited a crack onset strain of 17.23%. Notably, the stretchable OPVs retained over 80% of their initial PCE under 30% strain. These findings underscore the potential of conjugated and elastomeric dual‐network morphology in developing high‐performance stretchable electronics for various applications.

A nuclear jamming transition in vertebrate organogenesis.

Jamming of cell collectives and associated rigidity transitions have been shown to play a key role in tissue dynamics, structure and morphogenesis. Cellular jamming is controlled by cellular density and the mechanics of cell-cell contacts. However, the contribution of subcellular organelles to the physical state of the emergent tissue is unclear. Here we report a nuclear jamming transition in zebrafish retina and brain tissues, where physical interactions between highly packed nuclei restrict cellular movements and control tissue mechanics and architecture. Computational modelling suggests that the nuclear volume fraction and anisotropy of cells control the emerging tissue physical state. Analysis of tissue architecture, mechanics and nuclear movements during eye development show that retina tissues undergo a nuclear jamming transition as they form, with increasing nuclear packing leading to more ordered cellular arrangements, reminiscent of the crystalline cellular packings in the functional adult eye. Our results reveal an important role of the cell nucleus in tissue mechanics and architecture.

Effects of hydrostatic pressure on amorphous chiral materials: Impact on homochiral or heterochiral H-bond sequences

High pressure effects on static dielectric permittivity of homochiral and heterochiral N-acetyl-α-methyl-benzylamine (Nac-MBA) were investigated. For homochiral composition, the static permittivity increases of 178% with pressure at T = 388 K. Interestingly, as pressure continued increasing, εS drastically collapsed to reach ε∞=3±0.3. In the case of heterochiral composition, the static permittivity increases with pressure (in the same magnitude order as the pure enantiomer), and reaches a constant value depending on the isothermal temperature. Thus, the size of the H-bond aggregates is highly pressure sensitive, increasing up to a level that crystallization becomes unavoidable. For heterochiral composition, this process may be kinetically time consuming since the initial heterochiral H-bond aggregates need to be surrounded by their suitable neighbors in order to fulfilled the crystalline packing. The initial H-bond sequences are the precursors of the future crystalline arrangement under pressure application.

The impact of exchanging the light and heavy chains on the structures of bovine ultralong antibodies.

The third complementary-determining regions of the heavy-chain (CDR3H) variable regions (VH) of some cattle antibodies are highly extended, consisting of 48 or more residues. These `ultralong' CDR3Hs form β-ribbon stalks that protrude from the surface of the antibody with a disulfide cross-linked knob region at their apex that dominates antigen interactions over the other CDR loops. The structure of the Fab fragment of a naturally paired bovine ultralong antibody (D08), identified by single B-cell sequencing, has been determined to 1.6 Å resolution. By swapping the D08 native light chain with that of an unrelated antigen-unknown ultralong antibody, it is shown that interactions between the CDR3s of the variable domains potentially affect the fine positioning of the ultralong CDR3H; however, comparison with other crystallographic structures shows that crystalline packing is also a major contributor. It is concluded that, on balance, the exact positioning of ultralong CDR3H loops is most likely to be due to the constraints of crystal packing.

Deuteration of non-labile protium in starch: Biosynthesis and characterisation from yeast-derived starch granules

Deuterium labelling of the non-labile protium atoms in starch granules has been achieved for the first time, by growing genetically modified yeast on deuterated media. Mass spectrometry of the glucose monomers from digested starch showed 44 % average deuteration of the non-labile protium when grown on partially deuterated raffinose (with average deuteration 48 %); yielding starch with 26 % average overall deuteration. Non-labile deuteration was also demonstrated using D2O solvent in the culture medium. Solid-state NMR revealed that deuteration was not evenly distributed across the monomer, being highest at the C6 carbon and lowest at the C1 carbon. SANS revealed two structural features at q = 0.05 Å−1 and 0.4 Å−1, the first corresponding to a lamellar repeat of approximately 12–13 nm while the latter is consistent with B-type crystalline polymer packing. Furthermore, solvent contrast variation SANS analysis yielded a contrast match point of 66 mol% D2O indicative of approximately 30–35 % average deuteration of the bulk granules, consistent with mass spectroscopy. When coupled with the more traditional process of exchange of labile protium in the hydroxyl groups by D2O solvent exchange, the biosynthesis of highly deuterated starch opens new opportunities for neutron scattering experiments involving multicomponent starch-based systems.

Universal stress correlations in crystalline and amorphous packings.

We present a universal characterization of stress correlations in athermal systems, across crystalline to amorphous packings. Via numerical analysis of static configurations of particles interacting through harmonic as well as Lennard-Jones potentials, for a variety of preparation protocols and ranges of microscopic disorder, we show that the properties of the stress correlations at large lengthscales are surprisingly universal across all situations, independent of structural correlations, or the correlations in orientational order. In the near-crystalline limit, we present exact results for the stress correlations for both models, which work surprisingly well at large lengthscales, even in the amorphous phase. Finally, we study the differences in stress fluctuations across the amorphization transition, where stress correlations reveal the loss of periodicity in the structure at short lengthscales with increasing disorder.

Effects of chlorine and nitro groups on the crystal structure of novel 4-quinolinone derivatives from sulfonamide chalcone

This study explores the impact of introducing chlorine and nitro groups into two novel quinolone derivatives, (E)-3-(4-nitrobenzylidene)-2-(3-nitrophenyl)-2,3-dihydro-1-(phenylsulfonyl)-quinolin-4(1H)-one (NPQ) and (E)-3-(4-chlorobenzylidene)-2-(3-nitrophenyl)-2,3-dihydro-1-(phenylsulfonyl)-quinolin-4(1H)-one (CPQ), using experimental techniques and density functional theory (DFT). The research focuses on crystalline packing, conformational changes, and intermolecular interactions. The investigation reveals that weak non-classical hydrogen interactions, hydrophobic, and CH···π interactions, predominantly stabilize the crystal structures. These interactions, quantified through a Hirshfeld surface analysis. Additionally, the Fukui function analysis indicates antioxidant potential in the crystals. NPQ and CPQ exhibit a small energy gap, implying low kinetic stability, high reactivity, and reduced resistance to charge transfer when compared. These findings provide valuable insights into the structural and electronic properties of these quinolone derivatives, aiding the design of novel compounds with desired characteristics and applications. The DFT analysis utiliazsed the M062-X functional and the 6–311++G(d,p) basis set in the Gaussian 09 package, and the result was visualized using the GaussView software.

A soft crystalline packing with no metallic analogue.

A soft crystalline packing with no metallic analogue.

A copper(II) aminopyrimidinone complex: X-ray crystallography, computational analysis, dielectric spectroscopy and molecular docking

A new copper(II) complex with 2-amino-6-methylpyrimidin-4-(1H)-one, [Cu(C5H7N3O)4](NO3)2·H2O (Cupyrim), has been synthesized and studied by X-ray diffraction, elemental analysis and FT-IR spectroscopy. The Cu(II) is four-coordinate in a square planar geometry by four nitrogen atoms of the four organic ligands. Hirshfeld Surface Analysis was conducted to understand crystalline packing. Overall, the structure is maintained by metal coordination as well as strong and weak (C,N)–H···O hydrogen bonds and C–H…π interactions. The IR spectrum primary peaks have been assigned to the vibration modes of the ligand functional groups. An investigation of the inhibitory properties of Cupyrim toward “Cyclin-dependent Kinase 2” (CdK2) and “inducible nitric oxide synthase” (iNOS) proteins was aided by molecular docking research. According to molecular docking, Cupyrim exhibits promising inhibitory efficacy against Parkinson’s, schizophrenia, and Alzheimer’s disorders. The temperature dependence of the real and imaginary part of the dielectric permittivity was analyzed with the Cole-Cole formalism as well as DSC diagrams from 45-147 °C.

Proposed crystal structure of carbadox, C11H10N4O4

A model for the crystal structure of carbadox has been generated and refined using synchrotron X-ray powder diffraction data and optimized using density functional theory techniques. Carbadox crystallizes in space group P21 (#4) with a = 13.8155(3), b = 21.4662(1), c = 16.3297(3) Å, β = 110.0931(7)°, V = 4548.10(3) Å3, and Z = 16. The crystal structure is characterized by approximately parallel stacking of the eight independent carbadox molecules parallel to the bc-plane. There are two different molecular configurations of the eight carbadox molecules; five are in the lower-energy configuration and three are in a ~10% higher-energy configuration. This arrangement likely achieves the lowest-energy crystalline packing via hydrogen bonding. Hydrogen bonds link the molecules both within and between the planes. Each of the amino groups forms a N–H⋯O hydrogen bond to an oxygen atom of the 1,4-dioxidoquinoxaline ring system of another molecule. The result is four pairs of hydrogen-bonded molecules, which form rings with graph set R2,2(14). Variation in specimen preparation can affect the preferred orientation of particles considerably. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ (PDF®).

Position and Number Do Matter: Tuning Room Temperature Phosphorescence in Bromo‐1,8‐Naphthalimides through H‐Aggregation and Halogen Bonding

AbstractDevelopment of purely organic room temperature phosphors can often be obtained via introduction of heavy atoms into the organic scaffold. However, the task of controlling emission properties in room temperature phosphorescent (RTP) crystals via heavy atom substitution has met limited success. Herein, two classes of molecules (NIpBr1‐2 and NImBr1‐2) are designed by varying position (para and meta) as well as number of bromo substituents in 1,8‐naphthalimide to modulate intermolecular interactions and their phosphorescence properties. NIpBr2 features only halogen bonding. NIpBr, NImBr, and NImBr2 feature H‐aggregation in their crystalline packing wherein the efficiency of H‐aggregation increases as NIpBr &lt; NImBr &lt; NImBr2. NImBr2 also features halogen bonding in addition to H‐aggregation. Relative phosphorescence intensity, phosphorescence lifetime and quantum yield increase in the order NIpBr2 &lt; NIpBr &lt; NImBr &lt; NImBr2, endorsing cruciality of bromine atom positioning and numbering in tuning the RTP performance. Amplification of phosphorescence in meta derivatives over the para congeners leads to tunable emission color of the crystals from blue to orange. These results outline a predictive structure‐property relationship wherein judicious choice of both position and number of bromine substitution can help in regulating emission behavior, providing a major step forward in expanding the fundamentals of organic RTP.

Uncovering the Crystalline Packing Advantages of Asymmetric Y‐Series Acceptors for Efficient Additive‐Insensitive and Intrinsically Stable Organic Solar Cells

AbstractOrganic solar cells (OSCs) hold immense potential as renewable energy sources, but the performance‐stability conundrum remains a major obstacle on the road to OSC commercialization. To address this, in this study, molecular packing behaviors of representative state‐of‐the‐art Y‐series non‐fullerene acceptors (NFAs) are studied, focusing on their terminal group symmetries. Utilizing grazing‐incidence wide‐angle X‐ray scattering, the distinct crystalline packing structure of these NFAs is revealed. Remarkably, NFAs with asymmetric terminals exhibited excellent additive insensitivity and thermal stability for their crystalline structure, unlike their symmetric counterparts. Molecular dynamics simulations confirmed the stable and robust crystalline feature of asymmetric NFAs and attributed to their large molecular dipole moments. These findings showed the great potential of asymmetric NFAs in fabricating efficient and intrinsically stable additive‐free OSC devices for real applications.

Nanoparticle-directed bimodal crystallization of the quasi-1D van der Waals phase, Bi4I4.

Anisotropy often yields unexpected structures and properties in the solid state. In van der Waals (vdW) solids comprised of 1D or quasi-1D (q-1D) building blocks, anisotropy in both intra- and inter-chain directions results in an abundance of crystalline packing motifs and drastically altered physical states. Among these, structurally and chemically complex 1D/q-1D vdW solids that display topologically protected states, unique optical properties, and enhanced electrical transport properties in 1D are sought after owing to their potential as building blocks for next-generation quantum devices that approach the sub-nanometer regime. Yet, the access to such facet- and edge-specific physical states is still limited by the stochastic nature of micromechanical exfoliation. Here, we demonstrate that the representative Bi4I4 phase, an established pnictohalide q-1D vdW topological insulator in the bulk, can be crystallized from the vapor phase either into well-defined nanowires or quasi-2D nanosheets. We find that gold nanoparticles (Au NPs) on the growth substrate, in conjunction with the highly anisotropic structure of Bi4I4 common to many q-1D vdW crystals, direct the dimensionality of high-purity Bi4I4 nanostructures. Systematic variation of Au NP diameters, Bi : I precursor ratios, and growth-deposition temperatures reveal that Au NPs generally act as nucleation sites for vapor-solid (VS) growth of Bi4I4 nanowires. Strikingly, post-synthesis analyses of the elemental composition of 20 nm Au NPs on the substrate surface show an equisotichiometric 1 : 1 ratio of Bi to I within the Au NP that triggers the vapor-liquid-solid (VLS) growth of [001]-oriented quasi-2D nanosheets comprised of laterally-ordered [Bi4I4]n chains along the perpendicular [100] direction. We rationalize the observed bimodal growth pathways and the morphologically distinct nanostructures based on crystallization habits and orientations of the nanostructures, Bi : I ratios in the resulting Au NPs post-synthesis, and the orientation of stereochemically active Bi lone pairs between adjacent chains. We anticipate that these growth pathways are adaptable to the synthesis of emergent halide- and chalcogen-based 1D vdW nanocrystals with diverse physical and quantum properties.

Naturally J-aggregated F-BODIPYs: Self-assembly organization driven by substitution pattern

The development of self-assembled dyes able to display J-aggregation-induced emission has gained a renewed interest as an appealing and distinctive approach for the design of smart photoactive materials. F-BODIPY dyes have been exploited to this aim since J-type supramolecular organization has been effectively photoinduced under specific surrounding conditions (hydrophilic or constrained media) although, up to date, it has never been observed in pure organic media. Herein, we report the first systematic study of the self-assembly properties of F-BODIPYs in pure organic solvents and analyze in depth the control exerted by the substitution pattern of its carbon skeleton into the formation of emissive J-aggregates. Spontaneous J-aggregation in F-BODIPYs is evidenced by their lasing properties and supported by the analysis of their solid-state photophysics and X-ray crystalline packing as well as by molecular dynamics in solvent cages. These studies point out the key role of the stereoelectronic properties of the substituents orthogonally grafted at the dipyrrin core (meso and C-2 and C-6 positions) as the main driving force to control the molecular stacking arrangement of F-BODIPYs in common organic solvents. The understanding of the interplay between the molecular structure and the properties of the resulting aggregates sheds light on the workability of BODIPY-based self-assembly as a tool for advanced luminescent materials.

Crystal structure, hydrogen bond patterns, Hirshfeld surface analysis, and topological studies (NCI) of 1,5,5-trimethyl-imidazolidine-2,4-dione; an organic compound with high symmetry crystallizing in the tetragonal space group I4/m

The title compound, 1,5,5-trimethyl-imidazolidine-2,4‑dione was characterized by FT-IR, 1H NMR, and 13C NMR spectroscopy techniques. The crystal structure was established by single-crystal X-ray diffraction. The powder X-ray powder diffraction analysis confirms the phase purity of the crystalline sample. The hydantoin with formula C6H10N2O2 crystallizes in the tetragonal space group I4/m (N°87), Z=8, and unit cell parameters a=15.554(2) Å, c=6.623(6) Å. This space group is very infrequent to find in purely organic molecules and is since, in the asymmetric unit, the hydantoin ring lies on a mirror plane m. The crystalline packing is stabilized by the formation of intermolecular interactions of the strong hydrogen bond type of the N–H···O between the neighboring hydantoin rings. In addition, the crystalline structure presents the formation of weaker unconventional hydrogen bonds of the C–H···O type. These hydrogen bonds give rise to the formation of 8, 24, and 36-membered ring-type supramolecular structures described by the graphs R22(8), R44(24), and R88(36), respectively, which govern the packing of the supramolecular structure of 1,5,5-trimethyl-imidazolidine-2,4‑dione.Hirshfeld surface analysis of the crystal structure shows that the most important contributions for the crystal packing are from H···H (58.3%) and H··O/O··H (34.0%) interactions, which indicate that van der Waals interactions are the dominant forces in the crystal packing. Energy framework calculations suggest that the contacts formed between molecules are slightly electrostatic.These intermolecular interactions were also investigated through topological analysis of the electron density (ρ) employing the NCI method. Experimental and theoretical results obtained for this new hydantoin compound suggest that N–H···O and C–H···O interactions play an important role in the stabilization of its supramolecular structure.

Free Energy Perturbation Approach for Accurate Crystalline Aqueous Solubility Predictions.

Early assessment of crystalline thermodynamic solubility continues to be elusive for drug discovery and development despite its critical importance, especially for the ever-increasing fraction of poorly soluble drug candidates. Here we present a detailed evaluation of a physics-based free energy perturbation (FEP+) approach for computing the thermodynamic aqueous solubility. The predictive power of this approach is assessed across diverse chemical spaces, spanning pharmaceutically relevant literature compounds and more complex AbbVie compounds. Our approach achieves predictive (RMSE = 0.86) and differentiating power (R2 = 0.69) and therefore provides notably improved correlations to experimental solubility compared to state-of-the-art machine learning approaches that utilize quantum mechanics-based descriptors. The importance of explicit considerations of crystalline packing in predicting solubility by the FEP+ approach is also highlighted in this study. Finally, we show how computed energetics, including hydration and sublimation free energies, can provide further insights into molecule design to feed the medicinal chemistry DMTA cycle.

Metolazone co-crystals-loaded oral fast dissolving films: Design, optimization, and in vivo evaluation

This study aimed to formulate and optimize metolazone (MLZ) co-crystals incorporating fast-dissolving films (OFDFs) as an agreeable oral formulation for improving the bioavailability of the drug. The co-crystal formation between MLZ and different co-formers was performed using the solvent evaporation method. The MLZ co-crystal formula (MLZ-nicotinamide) with the highest dissolution parameters was loaded into OFDFs by the solvent casting method after being characterized by FT-IR, DSC, and PXRD. The formulated OFDFs were evaluated for their physicochemical properties. Using Statgraphics Centurion software, a full factorial design was used to examine the impact of formulation variables on the swelling index, the disintegration time, and the cumulative MLZ percent release after 10 min. The optimized OFDF was subjected to palatability, stability, and in vivo studies. Various co-formers lowered the melting point of MLZ, suggesting the development of different crystalline packing arrangements and the formation of co-crystals. All developed co-crystal formulations had higher values for relative dissolving rate (RD) and dissolution efficiency (DE%) when compared to pure MLZ. The obtained FTIR data could reflect the co-crystallization process between MLZ and nicotinamide, which was confirmed by the change of the PXRD pattern and the shift of the endothermic peak obtained by DSC. The optimized OFDF loaded with MLZ had a 4.57 swelling index, a 23.7 s disintegration time, and 99.8% MLZ released after 10 min. The optimized formula was stable for six months under the specified storage conditions. When evaluated in rabbits, the relative bioavailability of the optimized MLZ-OFDF was calculated to be approximately two-fold higher than that of the commercially available Efectinix® tablets.

Cascade Energy Transfer and White‐Light Emission in Chirality‐Controlled Crystallization‐Driven Two‐Dimensional Co‐assemblies from Donor and Acceptor Dye‐Conjugated Polylactides

AbstractAchieving predictable and programmable two‐dimensional (2D) structures with specific functions from exclusively organic soft materials remains a scientific challenge. This article unravels stereocomplex crystallization‐driven self‐assembly as a facile method for producing thermally robust discrete 2D‐platelets of diamond shape from biodegradable semicrystalline polylactide (PLA) scaffolds. The method involves co‐assembling two PLA stereoisomers, namely, PY‐PDLA and NMI‐PLLA, which form stereocomplex (SC)‐crystals in isopropanol. By conjugating a well‐known Förster resonance energy transfer (FRET) donor and acceptor dye, namely, pyrene (PY) and naphthalene monoimide (NMI), respectively, to the chain termini of these two interacting stereoisomers, a thermally robust FRET process can be stimulated from the 2D array of the co‐assembled dyes on the thermally resilient SC‐PLA crystal surfaces. Uniquely, by decorating the surface of the SC‐PLA crystals with an externally immobilized guest dye, Rhodamine‐B, similar diamond‐shaped structures could be produced that exhibit pure white‐light emission through a surface‐induced two‐step cascade energy transfer process. The FRET response in these systems displays remarkable dependence on the intrinsic crystalline packing, which could be modulated by the chirality of the co‐assembling PLA chains. This is supported by comparing the properties of similar 2D platelets generated from two homochiral PLLAs (PY‐PLLA and NMI‐PLLA) labeled with the same FRET pair.