Solid-state Properties Research Articles

Core- versus End-Alkylation: Tailoring Solid-State Structures and Properties of Near-Infrared-Absorbing Organic Semiconductors Based on Naphthodithiophenediones

Core- versus End-Alkylation: Tailoring Solid-State Structures and Properties of Near-Infrared-Absorbing Organic Semiconductors Based on Naphthodithiophenediones

Evaluation of aspartame as a co-former in the preparation of co-amorphous formulations of dipyridamole using spray drying

Co-amorphous systems (CAMs) have shown promise in addressing the challenges associated with poorly water-soluble drugs. However, the limited selection of co-formers and the use of lab-scale techniques for their preparation present challenges in fully utilizing the advantages of CAMs. In this study, we used aspartame (a methyl ester of the aspartic acid/phenylalanine) as a model dipeptide with the BCS class II drug dipyridamole, to prepare co-amorphous systems using spray drying. The feed solutions were prepared by dissolving the drug and co-former into methanol–water mixtures. The spray drying process was evaluated and solid-state properties were compared with those of the individual amino acids, amino acid mixtures and aspartame as co-formers. Co-amorphous systems prepared with aspartame (AspPhe) exhibited better solid-state properties, including a higher glass transition temperature (Tg), compared to the individual amino acids and the mixture of amino acids. Additionally, this formulation showed improved physical stability when stored at 25 °C/60 % RH conditions. Hirshfeld Surface (HS) analysis was employed to visualize and analyse the molecular interaction sites within the crystal structures of dipyridamole and aspartame. The observed interactions were then correlated with the molecular interactions identified through FT-IR spectroscopic analysis within the CAMs. The spectroscopic analysis revealed molecular interactions between the sites found at the shortest distances in the HS analysis. The dominant hydrogen bond interactions identified in the co-amorphous DPM-AspPhe system was found to contribute significantly to its improve stability. X-ray powder diffraction in non-ambient mode reveals that both temperature and humidity play a role in the crystallization of the co-amorphous DPM-AspPhe. Crystallization rates increased notably at high temperature and humidity. To predict stability under accelerated conditions, the crystallization rates from DPM-AspPhe were fitted to a modified Arrhenius equation. However, the predictive accuracy of the resulting model was limited to a specific range of conditions.

Facile Access to Benz[c,d]indolium-containing Dyes: C-N and C-C Bond Formation and Their Photophysical Properties

This work explores an efficient synthesis method for 1,8-Np derivatives, focusing specifically on the relatively inactive site (site II) of 1,8-Np, as well as the low-activity NH site present in secondary amine compounds. Derivatives Np-A-1∼9 are synthesized by forming C-N bonds with POCl3 acting as the activating reagent, achieving good yields (30∼62%). Next, substrate expansion on 1,8-Np proceed with other secondary amine compounds. Np-B and C are synthesized by forming C-N bonds, however, Np-D-1, 2 are synthesized by forming C-C bonds. This is a mild approach for forming C-N and C-C bonds, which is beneficial for the preparation of near-infrared (NIR) fluorescent dyes. Optical properties in solvents are discussed for Np-A∼D. This system shows large Stokes shifts (4513∼9105cm-1). The AIE phenomenon and solid-state emission properties are observed in Np-A-1∼9, which exhibit strong AIE phenomena, featuring 1.3 to 7.1-fold fluorescence intensity enhancement and solid fluorescence quantum yield ranging from 6.08 to 15.27%. The substitution on the indole unit is beneficial for enhancing the AIE effect and increasing the solid fluorescence quantum yield. Single crystal analysis and DFT calculation further elucidate the structures and the optical properties.

Exploring vacuum foam drying as an alternative to freeze-drying and spray drying for a human lipase

This article compares and explores vacuum foam-drying as an alternative drying technology to freeze-drying and spray drying for a recombinant human lipase as the model protein. Materials characteristics such as structure, surface composition and the solid-state properties of the dry materials were compared and investigated. Moreover, the technical functionality in terms of reconstitution characteristics and the lipase stability were also investigated. The stability of the lipase was evaluated through activity measurements. Sucrose and dextran D40 (40 kDa) were used as matrix former and the surfactant α-dodecyl maltoside was used as surface active additive. The study demonstrated that the drying technique greatly influenced the material structure and composition which in turn affected the reconstitution characteristics. The lipase was overrepresented at the material surface in declining order spray-dried > vacuum foam-dried > freeze-dried. The lipase activity was retained up to 10 % lipase content in solids, but at 20 % lipase a loss of activity was observed for all drying techniques. Phase separation in the solid material may be an explanation. Vacuum foam-drying shows promise as an alternative drying technique for the lipase, and potentially other proteins.

Preparation, characterization and modification of magnesium hydride for enhanced solid-state hydrogen storage properties

Magnesium–magnesium hydride (Mg–MgH2) system has attracted attention worldwide recently because of its simple hydrogenation-dehydrogenation process, the cost-effectiveness of the raw materials, and relatively high hydrogen storage capacity compared to the other metal-metal hydride systems. The present study deals with the optimization of the process parameters for the synthesis of magnesium hydride (MgH2) in sizable quantities using commercial-grade magnesium powder, characterization with respect to hydrogen storage capacity, by thermal dehydrogenation and pH-controlled aqueous hydrolysis. The thermal hydrogenation-dehydrogenation and mild acidified aqueous dehydrogenation behaviour of MgH2 were studied systematically to compare the decomposition kinetics and storage capacity. The superior catalytic effect of V2O5 on decreasing the onset-dehydrogenation temperature of MgH2 is demonstrated. The MgH2-5 wt. % mesoporous V2O5 sample starts releasing hydrogen at 220 °C, which is substantially less than the as-synthesized un-catalysed MgH2 under identical conditions which starts releasing hydrogen at 430 °C. The dehydrogenated MgH2-5wt. %V2O5 could be completely re-hydrogenated at 150 °C. Hydrolysis of as-synthesized MgH2 was demonstrated using an aqueous solution using tartaric acid and the dehydrogenation behaviour was co-related with the pH of the solution. More than 90% hydrogen yield was achieved by the hydrolysis of MgH2 in a tartaric acid solution of pH-4. Based on the result, a hydrogen gas dispenser using solid-state magnesium hydride as a hydrogen source is proposed for laboratory applications for the supply of ultra-pure hydrogen for various reactions and crystal growth experiments.

Preparation and solid-state characterization of two novel berberine chloride cocrystals with benzene derivatives

In this study, two novel salt-cocrystals of berberine chloride (BCl) with structurally similar benzene derivatives, i.e., 3-hydroxybenzoic acid (3HBA) and isophthalic acid (IA), were prepared. Their solid-state properties were characterized by complementary techniques, including single-crystal and powder X-ray diffractometry, thermogravimetric-differential scanning calorimetry, Fourier-transformed infrared spectroscopy, and dynamic moisture sorption analysis. Both cocrystals had lower hygroscopicity than BCl. An analysis of the properties of these cocrystals along with a previously published berberine chloride-resorcinol cocrystal suggests that a greater number of hydroxyl groups in these cocrystal formers may favor faster dissolution, measured by both intrinsic dissolution rate and powder dissolution.

Dual fungicides cocrystal of thiophanate-methyl and fludioxonil: Theoretical calculation and solubility studies

Thiophanate-methyl (TM) and Fludioxonil (FL) are extensively employed fungicides, yet they are hampered by issues of leaching and runoff for TM and limited solubility for FL. To overcome these limitations, we explored the active pharmaceutical ingredient (API)-API cocrystal approach to optimize the solubility of both compounds. In our study, a cocrystal of TM and FL with a stoichiometric ratio of 2:1 was synthesized and characterized using a suite of analytical techniques, including powder X-ray diffraction, single-crystal X-ray diffraction, FT-IR vibrational spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Quantum chemical calculations were utilized to elucidate the weak interactions within the TM-FL cocrystal. Notably, our solubility studies revealed that the cocrystal reduced TM solubility by 66.58 % and enhanced FL solubility by 48.41 %, which offers a significant reference for the simultaneous change of the solid-state properties of both APIs.

Solid-State Reversible Phase Transition and Photoluminescence Properties of Organic-Inorganic Hybrid Halide: (BTPA)2MnBr4.

Multifunctional materials have long been a popular research area, with organic-inorganic hybrids frequently utilized due to their diverse properties and versatile assembly techniques. In this context, a novel Mn-based organic-inorganic hybrid compound (BTPA)2MnBr4(1) was prepared, with strong green photoluminescence, phase transition under thermal stimulation, and two reversible dielectric-state switches. This compound exhibits strong green photoluminescence under ultraviolet excitation, boasting a quantum yield of 44.36%. Furthermore, it demonstrates a reversible ferroelastic phase transition at 358/348 K. The integration of temperature and photosensitivity in compound 1 opens up new avenues for the development and exploration of a broader spectrum of multifunctional phase transition materials.

Star-Shaped Polymers with Helical Polyacetylene Arms. Comparison of Solution- and Solid-State Properties with Linear Helical Polyacetylenes

Star-Shaped Polymers with Helical Polyacetylene Arms. Comparison of Solution- and Solid-State Properties with Linear Helical Polyacetylenes

Solid-state properties and antibiotic potency of levofloxacin – dicarboxylate salts prepared by the green method

This research dealt with the green methods to react levofloxacin (LF) with dicarboxylate acids: oxalic acid (OX), succinic acid (SA), malonic acid (MN), and maleic acid (MA) and investigated its impact on the LF’s stability, solubility, and antimicrobial potency, which never been reported before. Solvent-dropped grinding (SDG) using ethanol 95 % was used to prepare the organic antibiotic salts, reducing the solvent usage significantly compared to the conventional solvent evaporation method, supported with solid-state characterization using electrothermal, differential scanning calorimetry and powder X-ray diffractometry. Next, Fourier Transform Infrared Spectroscopy and Nuclear Magnetic Resonance (1H-NMR) confirmed and determined the interaction structure between LF and the acids. Afterward, the benefits of the LF-dicarboxylate salts were investigated, including stability, solubility, and antibiotic potency. The results demonstrated that the SDG could produce LF-OX hydrate, LF-SA hydrate, and anhydrous LF-MN in a (1:1) molar ratio, with a diffractogram never yet explained. Meanwhile, the LF-MA (1:1) salt solid-state structure was identical to the reported one. Notably, these LF-dicarboxylates showed better solubility, stability, and potency than LF alone, suggesting potential for further dosage formulations.

Creation of Excitation-Driven Hypervalent Tin(IV) Compounds For Aggregation-Induced Emission and Application to Thermoresponsive Luminescent Films Below Freezing Point.

Although many researchers have devoted their much effort to establish the strategy for developing a stimuli-responsive molecule and tuning of their properties according to the preprogrammed design, it is still challenging to create desired molecules from the scratch. We recently demonstrated that the molecules with a large structural difference between the theoretically optimized structures in the ground and excited states have a potential to exhibit stimuli-responsive luminescent properties. We defined these molecules as an excitation-driven molecule and have shown that they are a versatile platform for designing stimuli-responsive luminescent molecules. Herein, based on the concept of excitation-driven molecules, we show that the hypervalent tin-fused azomethine (TAm) compounds possessing aggregation-induced emission (AIE) properties can be obtained by simple chemical modification with a methyl group although conventional TAm derivatives are well known to be highly luminescent compounds in solution. Furthermore, by combining the solid-state luminescence property of AIE and the coordination number shifts of the hypervalent tin atom, the thermoresponsive films operating below the freezing point are fabricated with the polymer. In this study, we apply the concept of excitation-driven molecules to the hypervalent compounds and demonstrate to obtain the novel functional materials.

Encasing Triaryltriazine with a Bulky Chiral Cap: Luminescent Chiral Crystalline Molecular Rotors with Modulation of Solid-State Chiroptical Properties Mediated by Molecular Rotation.

A novel structural motif for luminescent chiral crystalline molecular rotors with chiroptical properties correlated with the rotational motion in crystalline media is presented. This scaffold incorporates bulky chiral caps consisting of a homochiral binaphthyl moiety with a triisopropylsilyl (TIPS) group into triaryltriazine, as confirmed by single-crystal X-ray diffraction (XRD) analysis. Variable-temperature solid-state 2H NMR studies revealed a 4-fold rotation of the phenylenes occurred in the rotor crystal between 263 and 333 K, while a steric rotor analogue shows no rotational motion. Notably, a reduction in the dihedral angle of the binaphthyl moiety upon heating was observed in the chiral rotors, and a corresponding alteration of the circular dichroism (CD) signal was detected in the solid-state, while those of the steric rotors showed no alteration by the temperature change. We propose that the fast rotation of the phenyl rings affects the motion of neighboring isopropyl groups, leading to steric repulsion with the binaphthyl moieties and thereby inducing its conformational change. Furthermore, the chiral rotors exhibited circularly polarized phosphorescence in the solid-state at low temperature, originating from rotational displacement of the phenylene on triphenyltriazine during structural relaxation in the excited state. Meanwhile, the steric rotors showed significant circularly polarized fluorescence induced by the suppressed molecular motion via a sterically hindered lattice environment in the excited state. These results indicate that the bulky chiral cap introduced into the triaryltriazines, acting as a luminescent chiral crystalline molecular rotor, can be a useful scaffold for the modulation of solid-state chiroptical properties via molecular rotational motions.

Spin-reorientation transition and exchange-bias effect in CeFe0.5Cr0.5O3 ceramics

The polycrystalline CeFe0.5Cr0.5O3 ceramics were synthesized by the solid-state method, whose structural and magnetic properties were systematically studied. With the interaction between Ce and Fe/Cr ions, a first-order spin-reorientation transition from Γ4 to Γ1 is observed over a wide temperature interval in CeFe0.5Cr0.5O3, which is remarkably sensitive to applied magnetic field. Interestingly, the exchange-bias effect is found in CeFe0.5Cr0.5O3 ceramics during the spin-reorientation transition, ascribed to the paramagnetic/antiferromagnetic system presented by the two interacting magnetic sublattices (Ce and Fe/Cr). The coexistence of spin-reorientation transition and exchange-bias effect is promising to expand the practical application of CeFe0.5Cr0.5O3 ceramics in multifunctional spintronics.

Development of Predictive Statistical Model for Gaining Valuable Insights in Pharmaceutical Product Recalls.

The rapid progress in artificial intelligence (AI) has revolutionized problem-solving across various domains. The global challenge of pharmaceutical product recalls imposes the development of effective tools to control and reduce shortage of pharmaceutical products and help avoid such recalls. This study employs AI, specifically machine learning (MI), to analyze critical factors influencing formulation, manufacturing, and formulation complexity which could offer promising avenue for optimizing drug development processes. Utilizing FDAZilla and SafeRX tools, an open database model was constructed, and predictive statistical models were developed using Multivariate Analysis and the Least Absolute Shrinkage and Selection Operator (LASSO) Approach. The study focuses on key descriptors such as delivery route, dosage form, dose, BCS classification, solid-state and physicochemical properties, release type, half-life, and manufacturing complexity. Through statistical analysis, a data simplification process identifies critical descriptors, assigning risk numbers and computing a cumulative risk number to assess product complexity and recall likelihood. Partial Least Square Regression and the LASSO approach established quantitative relationships between key descriptors and cumulative risk numbers. Results have identified key descriptors; BCS Class I, dose number, release profile, and drug half-life influencing product recall risk. The LASSO model further confirms these identified descriptors with 71% accuracy. In conclusion, the study presents a holistic AI and machine learning approach for evaluating and forecasting pharmaceutical product recalls, underscoring the importance of descriptors, formulation complexity, and manufacturing processes in mitigating risks associated with product quality.

Solid-State Structures and Properties of Lignin Hydrogenolysis Oil Compounds: Shedding a Unique Light on Lignin Valorization

This article explores the important, and yet often overlooked, solid-state structures of selected bioaromatic compounds commonly found in lignin hydrogenolysis oil, a renewable bio-oil that holds great promise to substitute fossil-based aromatic molecules in a wide range of chemical and material industrial applications. At first, single-crystal X-ray diffraction (SCXRD) was applied to the lignin model compounds, dihydroconiferyl alcohol, propyl guaiacol, and eugenol dimers, in order to elucidate the fundamental molecular interactions present in such small lignin-derived polyols. Then, considering the potential use of these lignin-derived molecules as building blocks for polymer applications, structural analysis was also performed for two chemically modified model compounds, i.e., the methylene-bridging propyl-guaiacol dimer and propyl guaiacol and eugenol glycidyl ethers, which can be used as precursors in phenolic and epoxy resins, respectively, thus providing additional information on how the molecular packing is altered following chemical modifications. In addition to the expected H-bonding interactions, other interactions such as π–π stacking and C–H∙∙∙π were observed. This resulted in unexpected trends in the tendencies towards the crystallization of lignin compounds. This was further explored with the aid of DSC analysis and CLP intermolecular energy calculations, where the relationship between the major interactions observed in all the SCXRD solid-state structures and their physico-chemical properties were evaluated alongside other non-crystallizable lignin model compounds. Beyond lignin model compounds, our findings could also provide important insights into the solid-state structure and the molecular organization of more complex lignin fragments, paving the way to the more efficient design of lignin-based materials with improved properties for industrial applications or improving downstream processing of lignin oils in biorefining processes, such as in enhancing the separation and isolation of specific bioaromatic compounds).

The broad-spectrum biocide triclosan trigonal crystal: Experimental and DFT-calculated structural, electronic and optical properties

Triclosan, a member of the broad-spectrum biocide class, has seen widespread usage in various household and healthcare-related products worldwide over the past 35 years. However, its extensive use has raised concerns regarding health and environmental impacts. Notably, there is a notable gap in our understanding of the solid-state properties of triclosan, encompassing both experimental aspects, such as optical absorption, and theoretical insights. Expanding upon the established trigonal crystal structure of triclosan, this study employs experimental techniques including X-ray and photoacoustic-based optical absorption, alongside density functional theory (DFT) calculations, to elucidate its structural, electronic, and optical characteristics. Employing the generalized gradient approximation (GGA) DFT exchange-correlation functional and accounting for dispersion effects, optimal lattice parameters were determined with small deviations from experimental measurements (<∼2.2%). The calculations predict that the triclosan trigonal crystal has very close direct band gaps of about 3.44 eV, almost identical to the value of 3.45 eV derived from photoacoustic optical absorption measurements. Analysis of the calculated optical absorption and complex dielectric function underscores the optical isotropy of solid state triclosan. Furthermore, effective mass computations, in conjunction with the band gap results, suggest that triclosan displays electronic characteristics akin to those of a wide direct gap semiconductor.

From 1D to 2D coordination polymers based on benzimidazole and dicarboxylate: Syntheses, structures, and fluorescence properties

Three new Zn(II)/Cd(II) coordination polymers (CPs), {[Zn(4pybbp)(fumarate)0.5(NO3)]·(DMA)2·(H2O)2.25}n (1), {[Zn(4pybbp)(glutarate)]·H2O}n (2), [Cd(4pybbp)(isophthalate)]n (3) (4pybbp = 2-(6-(1H-Benzo[d]imidazole-2-yl)pyridine-2-yl)-1-(pyridine-4-methylpyridine-1H-benzo[d]imidazole; DMA = dimethylacetamide) have been prepared using solvothermal method by introducing different dicarboxylate anion. Single crystal analysis shows that CP 1 and 2 are one-dimensional (1D) trapezoidal double-stranded and linear single-stranded structures, respectively, while CP 3 is two-dimensional (2D) planar structure. The structural disparities among the three coordination polymers can be ascribed to the size of d10 metal ions and the coordination mode of ligands. The solid-state fluorescence properties indicate that the fluorescence peaks of the coordination polymers 1–3 belong to the π*-π transition of the ligand 4pybbp, which occur significant blue-shift and enhancement. The order of fluorescence blue-shift is 1 > 2 > 3, which is consistent with the bond length order of Zn/Cd-Npyridine. The stronger fluorescence of the CPs than the ligand is due to the immobilization of the ligand through coordination, which reduces the energy loss of thermal vibration. Moreover, the fluorescence intensity of coordination polymers increases with the skeleton structure from 1D to 2D. Therefore, coordination and skeleton structure will affect the fluorescence of the coordination polymers.

Synthesis of polyfumarates containing a 4-tert-butylcyclohexyl group and unique solid-state properties based on the orientation of rigid poly(substituted methylene) chains

Synthesis of polyfumarates containing a 4-tert-butylcyclohexyl group and unique solid-state properties based on the orientation of rigid poly(substituted methylene) chains

On the importance of crystal structures for organic thin film transistors.

Historically, knowledge of the molecular packing within the crystal structures of organic semiconductors has been instrumental in understanding their solid-state electronic properties. Nowadays, crystal structures are thus becoming increasingly important for enabling engineering properties, understanding polymorphism in bulk and in thin films, exploring dynamics and elucidating phase-transition mechanisms. This review article introduces the most salient and recent results of the field.

Synchrotron radiation Fourier-transform infrared absorption measurements on the single-crystal dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene

The strong coupling of charge carriers with molecular vibrations is one essential characteristic of organic semiconductor materials as molecular solids. To address this question, fundamental solid-state properties of each molecular species are demanded not only for the electronic states but also for the vibrational characteristics. In the present study, Fourier-transform infrared absorption measurements were performed on single-crystal samples of dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) by using a linearly polarized synchrotron radiation light source. Molecular vibrational modes in a wavenumber range of 200–1600 cm−1 were reasonably assigned, and the Davydov splittings of several vibrational modes were resolved demonstrating intermolecular couplings of two DNTT molecules in the unit cell.