Unique Packing Research Articles

Engineering a Near-Infrared Spiro-Based Aggregation-Induced Emission Luminogen for DNAzyme-Sensitized Photothermal Therapy with High Efficiency and Accuracy.

Aggregation-induced emission luminogen (AIEgens)-based photothermal therapy (PTT) has grown into a sparkling frontier for tumor ablation. However, challenges remain due to the uncoordinated photoluminescence (PL) and photothermal properties of classical AIEgens, along with hyperthermia-induced antiapoptotic responses in tumor cells, hindering satisfactory therapeutic outcomes. Herein, a near-infrared (NIR) spiro-AIEgen TTQ-SA was designed for boosted PTT by auxiliary DNAzyme-regulated tumor cell sensitization. TTQ-SA with a unique molecular structure and packing mode was initially fabricated, endowing it with a strong AIE effect, favorable PL quantum yield, and good photothermal performance. DNAzyme, as a gene silencing tool, could alleviate antiapoptosis response during PTT. By integrating TTQ-SA and DNAzyme into folate-modified poly(lactic-co-glycolic acid) (PLGA) polymer, the as-fabricated nanosystem could promote cell apoptosis and sensitize tumor cells to PTT, thereby maximizing the therapeutic outcomes. With the combination of spiro-AIEgen-based PTT and DNAzyme-based gene silencing, the as-designed nanosystem showed promising NIR and photothermal imaging abilities for tumor targeting and demonstrated significant cell apoptotic, antitumor, and antimetastasis effects against orthotopic breast cancer. Furthermore, a synergistic antitumor effect was realized in spontaneous MMTV-PyMT transgenic mice. These findings offer new insights into AIEgen-based photothermal theranostics and DNAzyme-regulated tumor cell sensitization, paving the way for synergistic gene silencing-PTT nanoplatforms in clinical research.

Crystal structure of the GDP-bound human M-RAS protein in two crystal forms.

M-RAS plays a crucial role in the RAF-MEK signaling pathway. When activated by GTP, M-RAS forms a complex with SHOC2 and PP1C, initiating downstream RAF-MEK signal transduction. In this study, the crystal structure of the GDP-bound human M-RAS protein is presented with two forms of crystal packing. Both the full-length and truncated human M-RAS structures aligned well with the high-confidence section of the AlphaFold2-predicted structure with low r.m.s.d., except for the Switch regions. Despite high sequence similarity to the available mouse M-RAS structure, the full-length human M-RAS structure exhibits unique crystal packing. This inactive human M-RAS structure could offer novel insights for the design of selective compounds targeting M-RAS.

Iodo-bridged dicopper(I) complex containing a benzothienobenzothiophene unit: structure, characterization, and crystal-packing effects on solid-state photoluminescence

Abstract The title complex was newly synthesized by straightforward ligand substitution of a parent complex having a N2P2 set. The present complex had a deformed rhomboidal {Cu2I2} core with shortened Cu···Cu and prolonged I···I diagonals compared with those of the parent complex and formed one-dimensional channels filled with solvent molecules in crystals. The complex exhibited unusual red shift in solid-state photoluminescence assigned to halogen/metal-to-ligand charge transfer, indicating association of the unique crystal packing containing intramolecular electronic coupling between benzothienobenzothiophene moieties.

Indenoannulated Tridecacyclene: An All-Carbon Seven-Stage Redox-Amphoter.

We disclose an indenoannulated tridecacyclene comprising a central cyclooctatetraene moiety with multiple adjacent pentagonal rings which is accessible in a concise synthetic sequence. The saddle-shaped geometry of the non-benzenoid polycyclic scaffold and its unique packing behavior in the solid state were characterized by X-ray crystallography. In electrochemical studies, the compound undergoes seven reversible redox events comprising five reductions and two oxidations. The dicationic and dianionic species obtained by chemical oxidation and reduction, respectively, were characterized spectroscopically in solution. Density functional theory calculations were applied to provide insights into aromaticity evolution in the respective charged species, highlighting the beneficial effect of the non-benzenoid moieties on charge stabilization.

Exploring the formation and diversity of secnidazole cocrystals

This study investigates the cocrystallization of secnidazole (SNZ), a potent antimicrobial drug, with several coformers, overcoming the inherent stability challenges posed by its hemihydrate form to produce novel solid states. We successfully synthesized and characterized three novel cocrystals with carvacrol (CAR), fumaric acid (FMA), and 3,5-dinitrobenzoic acid (DNZ), employing synchrotron single crystal analysis to elucidate their structures. The application of Hirshfeld surface and 2D fingerprint plots further enriched our understanding of the unique packing arrangements within these cocrystals. Moreover, preliminary powder X-ray diffraction (PXRD) patterns hinted at the emergence of additional novel solid forms with salicylic acid (SLC), oxalic acid (OXA), succinic acid (SUC), citric acid (CTR), and thymol (THY). Supported by literature and a thorough analysis of molecular interactions, we propose the existence of pharmaceutical cocrystals among these newly identified solid forms. Our findings not only augment the repertoire of SNZ based pharmaceuticals but also accentuates the strategic utilization of supramolecular synthons, offering significant advancements in the understanding of novel solid form formation, and the critical role of hydrogen bonding in these processes.

Self-assembled soft alloy with Frank-Kasper phases beyond metals.

Soft building blocks, such as micelles, cells or soap bubbles, tend to adopt near-spherical geometry when densely packed together. As a result, their packing structures do not extend beyond those discovered in metallic glasses, quasicrystals and crystals. Here we report the emergence of two Frank-Kasper phases from the self-assembly of five-fold symmetric molecular pentagons. The μ phase, an important intermediate in superalloys, is indexed in soft matter, whereas the ϕ phase exhibits a structure distinct from known Frank-Kasper phases in metallic systems. We find a broad size and shape distribution of self-assembled mesoatoms formed by molecular pentagons while approaching equilibrium that contribute to the unique packing structures. This work provides insight into the manipulation of soft building blocks that deviate from the typical spherical geometry and opens avenues for the fabrication of 'soft alloy' structures that were previously unattainable in metal alloys.

Synthesis and Properties of Azahomocorannulenyl Cations and Radicals

AbstractCycloheptatrienyl (tropyl) molecules are representative non‐alternant hydrocarbons that offer interesting chemistry because of their unique structures and properties. However, there have been a limited number of polycyclic aromatic tropyl cations and radicals reported in the literature. Herein, we report the synthesis of a series of azahomocorannulene derivatives, where the key reactions are a 1,3‐dipolar cycloaddition of polycyclic aromatic azomethine ylides with dibenzotropone and a subsequent palladium‐catalyzed cyclization. X‐ray diffraction analysis revealed that the obtained azahomocorannulenyl cation and radical adopt planar structures and exhibit unique packing structures. Their electronic and optical properties were investigated experimentally and theoretically to reveal their aromatic character.

Synthesis and Properties of Azahomocorannulenyl Cations and Radicals.

Cycloheptatrienyl (tropyl) molecules are representative non-alternant hydrocarbons that offer interesting chemistry because of their unique structures and properties. However, there have been a limited number of polycyclic aromatic tropyl cations and radicals reported in the literature. Herein, we report the synthesis of a series of azahomocorannulene derivatives, where the key reactions are a 1,3-dipolar cycloaddition of polycyclic aromatic azomethine ylides with dibenzotropone and a subsequent palladium-catalyzed cyclization. X-ray diffraction analysis revealed that the obtained azahomocorannulenyl cation and radical adopt planar structures and exhibit unique packing structures. Their electronic and optical properties were investigated experimentally and theoretically to reveal their aromatic character.

Molecular "backbone surgery" of electron-deficient heteroarenes based on dithienopyrrolobenzothiadiazole: conformation-dependent crystal structures and charge transport properties.

Electron-deficient heteroarenes based on dithienopyrrolobenzothiadiazole (BTP) have been highly attractive due to their fascinating packing structures, broad absorption profiles, and promising applications in non-fullerene organic solar cells. However, the control of their crystal structures for superior charge transport still faces big challenges. Herein, a conformation engineering strategy is proposed to rationally manipulate the single crystal structure of BTP-series heteroarenes. The parent molecule BTPO-c has a 3D network crystal structure, which originates from its banana-shaped conformation. Subtracting one thiophene moiety from the central backbone leads to a looser brickwork crystal structure of the derivative BTPO-z because of its interrupted angular-shaped conformation. Further subtracting two thiophene moieties results in the derivative BTPO-l with a compact 2D-brickwork crystal structure due to its quasi-linear conformation with a unique dimer packing structure and short π-π stacking distance (3.30 Å). Further investigation of charge-transport properties via single-crystal organic transistors demonstrates that the compact 2D-brickwork crystal structure of BTPO-l leads to an excellent electron mobility of 3.5 cm2 V-1 s-1, much higher than that of BTPO-c with a 3D network (1.9 cm2 V-1 s-1) and BTPO-z with a looser brickwork structure (0.6 cm2 V-1 s-1). Notably, this study presents, for the first time, an elegant demonstration of the tunable single crystal structures of electron-deficient heteroarenes for efficient organic electronics.

Comparative analyses of Nonlinear Optical (NLO) properties, structural characterization and density functional theory of chloro-trifluoromethyl moiety chalcone derivatives for optical limiting application

This study focuses on the impact of substitutional positions on the nonlinear optical (NLO) and photophysical properties of four novel chalcone derivatives (I–IV). The grown crystals were characterized using FT-IR, NMR and single crystal X-ray diffraction (SCXRD) techniques, and the intermolecular interactions were studied by examining the unique packing motifs. The linear and 3rd-order NLO properties were experimentally determined using UV–Vis spectrometer and Z-scan setup with 637 nm continuous wave excitation, respectively. Compounds I–IV were studied theoretically using density functional theory (DFT) to support the experimental results. B3LYP functional was used to optimize the geometries, and the molecular properties of the compounds were determined via molecular electrostatic potential (MEP), natural population analysis (NPA), and localized orbital locator-π (LOL-π) analyze. The photophysical properties were analyzed using time-dependent DFT (TDDFT) using both CAM-B3LYP and B3LYP functionals to investigate the impact of the long-range correction. Inter-fragment charge transfer (IFCT) analysis and hole-electron analysis were employed to examine the linear optical properties and charge transfer mechanism. The NLO properties such as dipole moment (μ), polarizability (α), first and second hyperpolarizabilities (β and γ) were examined with the numerically differentiate analytic method using both functionals. Z-scan NLO data shows that the nonlinear refraction (NLR) coefficient of I–IV is significantly influenced by intermolecular interactions, specifically aggregation phenomena. Compound IV exhibits an exceptional nonlinear absorption (NLA) response and superior optical limiting properties compared to others attributed to its para-substituted strong electron-acceptor group (CF3) which results in highest transition dipole moment, lowest excitation energy, and well-defined charge transfer processes within its molecule. As a result, this suggests that it could be a potential candidate for NLO applications.

Rational Design and Reticulation of Infinite qbe Rod Secondary Building Units into Metal–Organic Frameworks through a Global Desymmetrization Approach for Inverse C3H8/C3H6 Separation

AbstractThe development of reticular chemistry has enabled the construction of a large array of metal–organic frameworks (MOFs) with diverse net topologies and functions. However, dominating this class of materials are those built from discrete/finite secondary building units (SBUs), yet the designed synthesis of frameworks involving infinite rod‐shaped SBUs remain underdeveloped. Here, by virtue of a global linker desymmetrization approach, we successfully targeted a novel Cu‐MOF (Cu‐ASY) incorporating infinite Cu‐carboxylate rod SBUs with its structure determined by micro electron diffraction (MicroED) crystallography. Interestingly, the rod SBU can be simplified as a unique cylindric sphere packing qbe tubule made of [43.62] tiles, which further connect the tritopic linkers to give a newly discovered 3,5‐connected gfc net. Cu‐ASY is a permanent ultramicroporous material featuring 1D channels with highly inert surfaces and shows a preferential adsorption of propane (C3H8) over propene (C3H6). The efficiency of C3H8 selective Cu‐ASY is validated by multicycle breakthrough experiments, giving C3H6 productivity of 2.2 L/kg. Density functional theory (DFT) calculations reveal that C3H8 molecules form multiple C−H⋅⋅⋅π and atypical C−H⋅⋅⋅ H−C van der Waals interactions with the inner nonpolar surfaces. This work therefore highlights the linker desymmetrization as an encouraging and intriguing strategy for achieving unique MOF structures and properties.

Rational Design and Reticulation of Infinite qbe Rod Secondary Building Units into Metal-Organic Frameworks through a Global Desymmetrization Approach for Inverse C3 H8 /C3 H6 Separation.

The development of reticular chemistry has enabled the construction of a large array of metal-organic frameworks (MOFs) with diverse net topologies and functions. However, dominating this class of materials are those built from discrete/finite secondary building units (SBUs), yet the designed synthesis of frameworks involving infinite rod-shaped SBUs remain underdeveloped. Here, by virtue of a global linker desymmetrization approach, we successfully targeted a novel Cu-MOF (Cu-ASY) incorporating infinite Cu-carboxylate rod SBUs with its structure determined by micro electron diffraction (MicroED) crystallography. Interestingly, the rod SBU can be simplified as a unique cylindric sphere packing qbe tubule made of [43 .62 ] tiles, which further connect the tritopic linkers to give a newly discovered 3,5-connected gfc net. Cu-ASY is a permanent ultramicroporous material featuring 1D channels with highly inert surfaces and shows a preferential adsorption of propane (C3 H8 ) over propene (C3 H6 ). The efficiency of C3 H8 selective Cu-ASY is validated by multicycle breakthrough experiments, giving C3 H6 productivity of 2.2 L/kg. Density functional theory (DFT) calculations reveal that C3 H8 molecules form multiple C-H⋅⋅⋅π and atypical C-H⋅⋅⋅ H-C van der Waals interactions with the inner nonpolar surfaces. This work therefore highlights the linker desymmetrization as an encouraging and intriguing strategy for achieving unique MOF structures and properties.

Polymorphism-driven Distinct Nanomechanical, Optical, Photophysical, and Conducting Properties in a Benzothiophene-quinoline.

Polymorphic forms of organic conjugated small molecules, with their unique molecular shapes, packing arrangements, and interaction patterns, provide an excellent opportunity to uncover how their microstructures influence their observable properties. Ethyl-2-(1-benzothiophene-2-yl)quinoline-4-carboxylate (BZQ) exists as dimorphs with distinct crystal habits - blocks (BZB) and needles (BZN). The crystal forms differ in their molecular arrangements - BZB has a slip-stacked column-like structure in contrast to a zig-zag crystal packing with limited π-overlap in BZN. The BZB crystals characterized by extended π-stacking along [100] demonstrated semiconductor behavior, whereas the BZN, with its zig-zag crystal packing and limited stacking characteristics, was reckoned as an insulator. Monotropically related crystal forms also differ in their nanomechanical properties, with BZB crystals being considerably softer than BZN crystals. This discrepancy in mechanical behavior can be attributed to the distinct molecular arrangements adopted by each crystal form, resulting in unique mechanisms to relieve the strain generated during nanoindentation experiments. Waveguiding experiments on the acicular crystals of BZN revealed the passive waveguiding properties. Excitation of these crystals using a 532 nm laser confirmed the propagation of elastically scattered photons (green) and the subsequent generation of inelastically scattered (orange) photons by the crystals. Further, the dimorphs display dissimilar photoluminescence properties; they are both blue-emissive, but BZN displays twice the quantum yield of BZB. The study underscores the integral role of polymorphism in modulating the mechanical, photophysical, and conducting properties of functional molecular materials. Importantly, our findings reveal the existence of light-emitting crystal polymorphs with varying electric conductivity, a relatively scarce phenomenon in the literature.

Electrosynthesis of Quasi-Epitaxial Crystals on Liquid Metals.

Electrosynthesis of single-crystalline metallic and intermetallic particles with a preferred orientation onto liquid metal electrodes has been performed. Liquid gallium electrodes immersed in aqueous alkaline electrolytes without any molecular additive or external solid seeding substrates were used to electroreduce separately Pb2+, Bi3+, Pd2+, and Mn2+. The crystallinity, composition, and orientation of the electrodeposition products were characterized by using scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, grazing incidence X-ray diffraction, and energy-dispersive X-ray spectroscopy. Electrodeposition of Pb and Bi results in the incipient formation of two-dimensional (2D) nuclei that subsequently direct the growth of Pb and Bi single crystals along the most close-packed [111] and [0001] directions, respectively. The absence of any intervening surface oxides and a low electroreduction flux are necessary to avoid polycrystalline dendrite formation. Under comparable conditions, the electrodeposition of Pd and Mn results in single-crystalline intermetallic particles at the interface. Each crystal exhibits a preferred orientation consistent with the unique atomic packing of the near-surface region of the liquid Ga. The presented study suggests a new concept in electrodeposition processes where the liquid metal structure imparts quasi-epitaxial growth in a system in which the electrode material specifically has no crystallinity or long-range order. This study is thus the first demonstration of highly oriented electrodeposition at a liquid/liquid interface under ambient conditions, highlighting the unique solvation environment of liquid metal interfaces for forming thin metallic and intermetallic films.

Synthesis of Heptagon-Containing Polyarenes by Catalytic C-H Activation.

Nanocarbons incorporating non-hexagonal aromatic rings - such as five-, seven-, and eight-membered rings - have various intriguing physical properties such as curved structures, unique one-dimensional packing, and promising magnetic, optical, and conductivity properties. Herein, we report an efficient synthetic approach to polycyclic aromatics containing seven-membered rings via a palladium-catalyzed intramolecular Ar-H/Ar-Br coupling. In addition to all-hydrocarbon scaffolds, heteroatom-embedded heptagon-containing polyarenes can be efficiently constructed with this method. Rhodium- and palladium-catalyzed sequential six- and seven-membered ring formations also afford complex heptagon-containing molecular nanocarbons from readily available arylacetylenes and biphenyl boronic acids. Detailed mechanistic analysis by DFT calculations showed the feasibility of seven-membered ring formation by a concerted metalation-deprotonation mechanism. This reaction can serve as a template for the synthesis of a wide range of seven-membered ring-containing molecular nanocarbons.

Insight on the Intracellular Supramolecular Assembly of DTTO: A Peculiar Example of Cell-Driven Polymorphism.

The assembly of supramolecular structures within living systems is an innovative approach for introducing artificial constructs and developing biomaterials capable of influencing and/or regulating the biological responses of living organisms. By integrating chemical, photophysical, morphological, and structural characterizations, it isshown that the cell-driven assembly of 2,6-diphenyl-3,5-dimethyl-dithieno[3,2-b:2',3'-d]thiophene-4,4-dioxide (DTTO) molecules into fibers results in the formation of a "biologically assisted" polymorphic form, hence the term bio-polymorph. Indeed, X-ray diffraction reveals that cell-grown DTTO fibers present a unique molecular packing leading to specific morphological, optical, and electrical properties. Monitoring the process of fiber formation in cells with time-resolved photoluminescence, it isestablished that cellular machinery is necessary for fiber production and a non-classical nucleation mechanism for their growth is postulated. These biomaterials may have disruptive applications in the stimulation and sense of living cells, but more crucially, the study of their genesis and properties broadens theunderstanding of life beyond the native components of cells.

Crystal Structure Analysis, Stability, Phase Transformation and Selective Nucleation Mechanism of Fluralaner Polymorphs

To better understand and control the crystallization of different polymorphs, a comprehensive crystal structure analysis was conducted by using fluralaner as a model compound, and the thermodynamic stability, phase transformation, and selective nucleation mechanisms were studied. Various analytical techniques such as powder X-ray diffraction, thermal analysis, and FT-IR spectra were used to comprehensively characterize Form I, Form Ⅱ, and Form III of fluralaner, and it was found that there is structural similarity between Form I and Form III, which was further confirmed by single crystal X-ray diffraction. However, it was found that Form Ⅱ had unique molecular conformation and packing pattern. The lattice energy was calculated by Materials Studio 7.0 and the thermodynamic stability of three forms was explored by phase transformation experiments, which suggested that the order of thermodynamic stability was Form Ⅱ > Form I > Form III. The selective nucleation of Form I and Form III with similar structure was studied through FT-IR spectra and molecular dynamics simulations. The results indicated that the addition of n-hexane may hinder the solute–solute interaction in the solution, thus resulting in the nucleation of different polymorphs.

Scalable High Tensile Modulus Composite Laminates Using Continuous Carbon Nanotube Yarns for Aerospace Applications.

An approach is established for fabricating high-strength and high-stiffness composite laminates with continuous carbon nanotube (CNT) yarns for scaled-up mechanical tests and potential aerospace structure applications. Continuous CNT yarns with up to 80% degree of nanotube alignment and a unique self-assembled graphitic CNT packing result in their specific tensile strengths of 1.77 ± 0.07 N/tex and an apparent specific modulus of 92.6 ± 3.2 N/tex. Unidirectional CNT yarn reinforced composite laminates with a CNT concentration of greater than 80 wt % and minimal microscale voids are fabricated using filament winding and aerospace-grade resin matrices. A specific tensile strength of up to 1.71 GPa/(g cm-3) and specific modulus of 256 GPa/(g cm-3) are realized; the specific modulus exceeds current state-of-the-art unidirectional carbon fiber composite laminates. The specific modulus of the laminates is 2.76 times greater than the specific modulus of the constituent CNT yarns, a phenomenon not observed in carbon fiber reinforced composites. The results demonstrate an effective approach for fabricating high-strength CNT yarns into composites for applications that require specific tensile modulus properties that are significantly beyond state-of-the-art carbon fiber composites and potentially open an unexplored performance region in the Ashby chart for composite material applications.

Pandian Pickles: value or volume?

Research methodology This study adopted interview methods and field visits to collect the data. An audio recording was done for the whole interview and presented as facts in this case. Field visits were done to see the packs and understand the consumers and their purchase habits of pickles. Case overview/synopsis Pandian Pickles is a pickle manufacturer located in Madurai, Tamil Nadu, a state in the southern part of India. Mr Kandasamy, one of the partner of the Pandian pickle, had been thinking of ways to grow the business. Pandian Pickles dominated the low-price unit (LPU) market with a unique packing of pickles done in “arecanut” leaf. This added a unique flavour to their pickles. Mr Kandasamy envisioned to grow the business by introducing higher stock-keeping units in the form of jars and tap the middle class and the upper-middle-class segments in the market. In this category, there were much more prominent and branded players. Being a small regional player, Govindan wondered how Pandian Pickles would take these more prominent players in the industry head-on. Complexity academic level The case is ideally suited for discussing the concept of product line stretching, particularly in the product mix strategies of a small and medium enterprise (SME). The case can best fit into the courses such as Entrepreneurship Development, Product and Brand Management, Marketing Management for the Undergraduate levels and in the courses such as Strategic Marketing, Bottom of the Pyramid Markets and Strategies Management of SMEs in the postgraduate levels.

Triply-Reduced Hexa-peri-hexabenzocoronenes: Solid-State Structures and Magnetic Properties

Discotic polycyclic aromatics have attracted great interest in both fundamental chemistry and material science due to their degenerate frontier orbitals, high molecular symmetry, unique solid-state packing, and ability to bear a certain number of unpaired electrons that can be applied in molecular spintronics and quantum computing. In this work, chemical reduction of hexa-peri-hexabenzocoronenes, HBC (1) and tBu-HBC (2), as “superbenzenes”, has been investigated with K metal in THF solution. These reactions readily afforded the triply reduced HBC-based products which have been isolated as single-crystalline materials. The X-ray diffraction study confirmed the formation of π-complexes [K+(18-crown-6)(THF)2][{K+(18-crown-6)}2(13–)] (3) and [K+(18-crown-6)(THF)2][{K+(18-crown-6)}2(23–)] (4). In 3 and 4, two potassium ions were found to bind the central six-membered rings of 13– and 23– with one potassium counterion remaining solvent-separated from the complexes. A notable geometry distortion of the HBC core upon three-electron acquisition and metal binding was revealed in both complexes. The presence of bulky substituents in 2 affected the coordination and crystal packing of otherwise similar building units in 4 vs 3. The magnetic properties of 4 supported the existence of a well-isolated S = 3/2 ground state of the 23– triradical in the solid state.