Acid Molecules Research Articles

Comprehensive Methodology for Evaluating the Drug Loading of Iron Oxide Nanoparticles Using Combined Magnetometry and Mössbauer Spectroscopy

A methodology for the quantitative estimation of the drug loading of iron oxide-based magnetic nanoparticles by corroborating magnetometry and Mössbauer spectroscopy investigations is reported. The proposed methodology is exemplified in the case of two series of nanoparticles, namely Fe3O4 nanoparticles covered with citric acid molecules and further functionalized with doxorubicin, and Fe3O4 nanoparticles covered with L-Cysteine molecules and further functionalized with doxorubicin. The general idea of the proposed methodology is to probe the real magnetic structure of the magnetic core via low-temperature Mössbauer spectroscopy for the correct estimation of the spontaneous magnetization of the magnetic core. It subsequently uses the ratio between the spontaneous magnetization of the covered nanoparticles and that of the magnetic core for the reliable and nondestructive evaluation of the nanoparticle loading by organic molecules. Although the methodology is exemplified in the case of magnetite-based nanoparticles, it can be successfully considered for a large class of medicine-loaded Fe-containing magnetic nanoparticles where 57Fe Mössbauer spectroscopy can be applied.

Protoporphyrin IX-modified chitosan/sodium alginate based cryogels for rapid hemostasis and antibacterial photodynamic therapy of infected wound healing.

Due to the porous and interconnected structure, cryogels significantly facilitate blood exudate absorption and support rapid hemostasis as novel wound dressings. However, cryogels suffer from insufficient inherent antibacterial properties, which seriously limits their clinical applications. Herein, we developed a chitosan (CHI) and sodium alginate (SA) composite-based antibacterial photodynamic therapy (aPDT) cryogel for rapid hemostasis and infected wound healing. In this cryogel, the photosensitizer protoporphyrin IX (PpIX) was chemically immobilized onto CHI (CHI-PpIX), while the phenylboronic acid (PBA) molecules were coupled onto SA (SA-PBA). The resulting CHI-PpIX/SA-PBA (CPSP) hydrogel was created by mixing CHI-PpIX and SA-PBA, followed by freeze-drying to form the CPSP cryogel. Through forming dynamic boronic ester bonds between PBA and diol groups on bacterial cell walls, CPSP was endowed with bacterial capturing capacity and enhanced aPDT. In vitro antibacterial experiments revealed its enhanced aPDT efficiency owing to PBA-mediated bacterial targeting. In addition, in vivo assays demonstrated its effective hemostatic, antibacterial and wound healing-promoting capacities. By effectively integrating aPDT with bacterial capturing capabilities and addressing the limitations of existing wound dressings, the CPSP cryogel offers a promising solution for rapid hemostasis and the treatment of infected wounds.

Pollution analysis of micro/nano meters glass particles and benzene produced from the friction cleaning process for the recovery of waste glass

Friction cleaning can effectively remove the paint coating (adhesive organic impurities) on the surface of waste glass, and promote the closed-loop recovery of urban silicic acid resources in industrial applications. However, due to a large number of mechanical collisions and wear during use, it is easy to produce powder dust and organic waste gas, and the pollution characteristics and mechanism have not been studied. In this study, the ball milling experiment was designed and the pollutants were tested and evaluated. The results show that a large number of micro/nano meters glass particles with an average size of less than 4.5 μm are generated by low-speed ball milling, and the risk of inhalation is as high as 50.75 mg/kg·m3. Main organic waste gases include cyclopropane, hexane, but-2-ene, and benzene with the value of Incremental lifetime cancer risk reaching 3.4 × 10−2 indicating definite carcinogenic risks for benzene exposure. The C–C bond between hydroxyl acrylic acid molecules and the C–O bond between phenolic propylene oxide molecules are easily broken to form small molecular chains, and the complex product is due to the complex cross-linking with the silane coupling agent. It is suggested that a special dust collector for micro/nano meters glass particles should be added while adopting an activated carbon catalytic combustion process to treat VOCs in the exhaust gas. This study revealed the contamination of micro/nano meters glass particles and benzene during friction cleaning to remove organic coatings in waste glass recycling.

Ginkgolic acid inhibits Ebola virus transcription and replication by disrupting the interaction between nucleoprotein and VP30 protein.

The Ebola virus, a filovirus, has been responsible for significant human fatalities since its discovery. Despite extensive research, effective small-molecule drugs remain elusive due to its complex pathogenesis. Inhibition of RNA synthesis is a promising therapeutic target, and the VP30 protein plays a critical role in this process. The interaction between VP30 and the nucleoprotein (NP) is essential for viral replication. We identified ginkgolic acid as a small molecule with strong affinity for VP30, which was validated through multiple assays, including thermal shift, surface plasmon resonance, fluorescence polarization, pull-down, and co-immunoprecipitation. The antiviral efficacy of ginkgolic acid was demonstrated in the EBOV transcription- and replication-competent virus-like particle (trVLP) system. Furthermore, we resolved the crystal structure of the VP30-ginkgolic acid complex, revealing two ginkgolic acid molecules located at the VP30/NP interaction interface. This structural information provides insight into the molecular basis of ginkgolic acid's antiviral activity and suggests a novel therapeutic strategy targeting the VP30/NP interaction.

Raman and DFT study of non-covalent interactions in liquid benzophenone and its solutions

Analysis of intermolecular interactions in liquid benzophenone and its solutions in acetone and acetic acid by Raman spectroscopy and quantum-chemical simulation is presented. The results of the experiment show that in binary solutions of benzophenone, a red shift was observed for the C ˭ O stretching band, and a blue shift was observed for the C–H stretching and breathing bands. Such shifts were predicted to occur due to weak (non-classical) hydrogen bonds of C–H⋅⋅⋅O ˭ C type between benzophenone and solvent molecules. The nature and strength of solute-solvent interactions are discussed. The electron density distribution in benzophenone and its complexes with acetone and acetic acid molecules was visualized using the molecular electrostatic potential surface. The electronic properties of the molecular complexes were characterized using the frontier molecular orbitals and localization functions.

Introduce a novel, extremely sensitive aptamer against staphylococcal enterotoxin type D.

Staphylococcus aureus (S. aureus) is a globally prevalent foodborne pathogen responsible for significant public health concerns. Staphylococcal food poisoning (SFP) results from staphylococcal enterotoxins (SEs) produced by specific strains of S. aureus. Rapid and effective detection of SEs remains a significant challenge for public health authorities. Aptamers, short single-stranded DNA(ssDNA), RNA, or synthetic xeno nucleic acid (XNA) molecules, exhibit high affinity for binding to their specific targets. Due to their unique properties, including low production costs, ease of chemical modification, high thermal stability, and reproducibility, aptamers present a viable alternative to antibodies for diagnostic and therapeutic applications. This research aimed to isolate high-affinity ssDNA aptamers with specificity for staphylococcal enterotoxin D (SED). The systematic evolution of ligands by the exponential enrichment (SELEX) method was utilized to identify specific aptamers. These aptamers were then validated using enzyme-linked apta-sorbent assay (ELASA) and surface plasmon resonance (SPR) to assess their binding characteristics and affinity. SELEX successfully identified aptamers with strong binding affinity to SED. Among the identified candidates, one aptamer, Aptamer 1, exhibited the highest specificity for SED with a dissociation constant (KD) of 4.4 ± 2.26 nM. The limit of detection (LOD) for SED using this aptamer was determined to be 45 nM. The findings indicate that the ELASA system designed using the aptamer developed in this study demonstrates higher specificity, sensitivity, and reproducibility in detecting enterotoxin D. This novel aptamer offers significant potential for applications in diagnostic platforms targeting S. aureus enterotoxins.

Interspecies interactions mediated by arginine metabolism enhance the stress tolerance of Fusobacterium nucleatum against Bifidobacterium animalis.

Colorectal cancer (CRC) is a common cancer accompanied by microbiome dysbiosis. Exploration of probiotics against oncogenic microorganisms is promising for CRC treatment. Here, differential microorganisms between CRC and healthy control were analyzed. Antibacterial experiments, whole-genome sequencing, and metabolic network reconstruction were combined to reveal the anti-Fusobacterium nucleatum mechanism, which was verified by co-culture assay and mendelian randomization analysis. Sequencing results showed that F. nucleatum was enriched in CRC, yet Bifidobacterium animalis decreased gradually from healthy to CRC. Additionally, F. nucleatum could be inhibited by B. animalis. Whole-genome sequencing of B. animalis showed high phylogenetic similarity with known probiotic strains and highlighted its functions for amino acid and carbohydrate metabolism. Metabolic network reconstruction demonstrated that cross-feeding and specific metabolites (acidic molecules, arginine) had a great influence on the coexistence relationship. Finally, the arginine supplement enhanced the competitive ability of F. nucleatum against B. animalis, and the mendelian randomization and metagenomic sequencing analysis confirmed the positive relationship among F. nucleatum, arginine metabolism, and CRC. Thus, whole-genome sequencing and metabolic network reconstruction are valuable for probiotic mining and patient dietary guidance.IMPORTANCEUsing probiotics to inhibit oncogenic microorganisms (Fusobacterium nucleatum) is promising for colorectal cancer (CRC) treatment. In this study, whole-genome sequencing and metabolic network reconstruction were combined to reveal the anti-F. nucleatum mechanism of Bifidobacterium animalis, which was verified by co-culture assay and mendelian randomization analysis. The result indicated that the arginine supplement enhanced the competitive ability of F. nucleatum, which may be harmful to F. nucleatum-infected CRC patients. B. animalis is a potential probiotic to relieve this dilemma. Thus, using in silico simulation methods based on flux balance analysis, such as genome-scale metabolic reconstruction, provides valuable insights for probiotic mining and dietary guidance for cancer patients.

Investigating Raman peak enhancement in carboxyl-rich molecules: insights from Au@Ag core-shell nanoparticles in colloids

Surface-enhanced Raman scattering (SERS) is a promising analytical technique with applications in environmental monitoring, healthcare, and the biopharmaceutical industry. While SERS has been successfully applied to molecules such as 4-mercaptobenzoic acid and other thiol- and amine-containing compounds, there is limited research on its detection capabilities for molecules rich in carboxyl groups or unsaturated bonds, such as citric acid. This study investigates the SERS enhancement of Au@Ag core-shell nanoparticles in response to citric acid and other molecules with carboxyl and unsaturated bonds. We compare the SERS behavior of nanoparticles in freshly prepared and aged sodium citrate solutions to identify differences in Raman peak enhancement. Our findings show that the Au@Ag core-shell nanoparticles exhibit significant SERS enhancement when exposed to citric acid and other related compounds. The enhancement varies based on the age of the sodium citrate solution, which influences the structural properties of the nanoparticles. This work opens avenues for further research and applications in biological monitoring, environmental testing, and the pharmaceutical industry.

Unraveling the Role of Functional Groups of Terephthalate in Enhancing the Electrochemical Oxygen Evolution Reaction of Nickel-Organic Framework Nanoarrays.

The platelike nickel-terephthalate-type metal-organic framework nanoarrays (Ni-BDC NAs) on carbon cloth are obtained by employing agaric-like Ni(OH)2 NAs as sacrificial templates. The microenvironment of Ni-BDC NAs is modulated by various neighboring functional groups (-NH2, -NO2, and -Br) on the carboxylate ligand, exerting minimal destructive effects on the structure and morphology of Ni-BDC NAs. The electrochemical oxygen evolution reaction (OER) of Ni-BDC-NH2 NAs, Ni-BDC-NO2 NAs, and Ni-BDC-Br NAs exhibited a significant enhancement compared to that of Ni-BDC NAs alone, as evidenced by both experimental and theoretical assessments. The presence of neighboring groups exerts a positive influence on the electronic coupling between Ni and O atoms, thereby facilitating the thermodynamically favorable formation of *O intermediates on Ni sites and accelerating the kinetics of the OER. The findings presented here provide valuable insights for the design and utilization of carboxylic acid molecules with functional group effects, enhancing the activity of the OER across diverse Ni centers.

Tannic acid-modified FK506-loaded nanoparticles targeting lymph nodes for acute heart transplant rejection treatment.

Significant efforts have been made to deliver immunosuppressants-loaded nanoparticles (NPs) to lymph nodes (LNs) to mitigate transplant rejection. However, conventional administration techniques encounter challenges in enhancing the retention of NPs in the LNs. Attributing the strong affinity of tannic acid (TA) molecules to the elastin of LN conduits, we developed a novel formulation of NPs encapsulating Tacrolimus (FK506), and subsequently modified with TA to produce TA-FNP with a final diameter of approximately 86.07 ± 2.78 nm. These particles could traverse the the intercellular gaps in the lymphatic endothelial cells layers, enter the paracortex through LN capsule-associated conduits, and releases FK506 to inhibit the activation and proliferation of allogeneic T cells. Our finding demonstrated that TA-FNP could accumulate in LNs, significantly increasing the local concentration of FK506 from 69.06 ± 21.96 ng/g to 1041.28 ± 343.59 ng/g compared to the free FK506 treatment group. Subsequently, the therapeutic efficacy of TA-FNP was assessed in heart transplantation model, where treatment with TA-FNP resulted in decreased T cells infiltration within the grafts, reduced rejection grades, and a significant extension of graft survival time. In contrast, FNP without TA showed relatively poor therapeutic outcomes. Consequently, this study reveals a promising strategy utilizing TA to enhance the prolonged retention of FK506 within LNs, underscoring its potential therapeutic application in preventing heart transplant rejection.

Sulfonic acid functionalized β-amyloid peptide aggregation inhibitors and antioxidant agents for the treatment of Alzheimer's disease: Combining machine learning, computational, in vitro and in vivo approaches.

Alzheimer's disease (AD) is characterized as a neurodegenerative disorder that is caused by plaque formation by accumulating β-amyloid (Aβ), leading to neurocognitive function and impaired mental development. Thus, targeting Aβ represents a promising target for the development of therapeutics in AD management. Several functionalized sulfonic acid molecules have been reported, including tramiprosate prodrug, which is currently in clinical trial III and exhibits a good response in mild to moderate AD patients. Therefore, expanding upon this approach, we hypothesized that the sulfonic acid functionalized aromatic class molecule might demonstrate a good inhibitory effect against β-amyloid aggregation, leading to a decrease in the progression burden of AD. We used computational and in vitro approaches to establish effective compounds. As a result, three potent hit molecules were selected based on binding score as well as availability. In the case of safety profile of compounds, in vitro using human neuroblastoma SH-SY5Y cells and in vivo using C. elegans was performed at doses up to 500 μM; no difference in viability was exhibited between control and treatment groups. However, H2O2-induced ROS stress was significantly reduced in neuroblastoma cells after treatment. The AFM and ThT-embedded β-amyloid1-42 kinetic studies confirmed B-PEA-MBSA and H-HPA-NSA potency. H-HPA-NSA arrested elongation phase of Aβ aggregation in kinetic study at a lower concentration (10 μM), while B-PEA-MBSA reduced the intensity of stationary phase at a dose of 100 μM. Thus, based on the outcomes, it can be suggested that B-PEA-MBSA and H-HPA-NSA can prevent β-amyloid aggregation with mild to moderate AD.

Designing High Content Carbonylated β-Cyclodextrin/PBI Mixed Matrix Membrane as HT-PEM to Reduce H3PO4 Loss.

The high-temperature proton exchange membranes suffer from weak binding strength for phosphoric acid molecules, which seriously reduce the fuel cell efficiency, especially operation stability. Introduction of microporous material in the membrane can effectively reduce the leaching of phosphoric acid. However, due to the poor compatibility between the polymer and fillers, the membrane's performance significantly reduced at high fillers content. Therefore, in this work, the strategy of micropore confinement was developed; the β-cyclodextrin was carbonylated and introduced into PBI casting solution as solution state rather than dry powder for reducing the interface energy between two phases, thus further reducing interface defects and increasing the content of effective confined micropores within the membrane. By this way, carbonylated β-cyclodextrin/PBI (50 wt %) mixed matrix membranes were obtained, the proton conductivity reached 142 ± 4 mS cm-1, while the conductivity attenuation was only 16.6%.

As a reliability measure for protein, nucleic acid, and small molecule atomic coordinate models derived from 3DEM density maps.

Atomic coordinate models are important in the interpretation of 3D maps produced with cryoEM and sub-tomogram averaging in cryoET, or more generically, 3D electron microscopy (3DEM). In addition to visual inspection of such maps and models, quantitative metrics convey the reliability of the atomic coordinates, in particular how well the model is supported by the experimentally determined 3DEM map. A recently introduced metric, , was shown to correlate well with the reported resolution of the map for well-fitted models. Here we present new statistical analyses of based on its application to 10,000 maps and models archived in EMDB and PDB. Further we introduce two new metrics based on : and to compare a map and model to all entries in the EMDB and those with similar resolution respectively. We also explore through illustrative examples of proteins, nucleic acids, and small molecules how can indicate whether the atomic coordinates are well-fitted to 3DEM maps and whether some parts of a map may be poorly resolved due to factors such as molecular flexibility, radiation damage, and/or conformational heterogeneity. Lastly, we show examples of how can effectively be converted to atomic . These analyses provide a basis for how can be interpreted effectively to evaluate 3DEM maps and atomic coordinate models prior to publication and archiving.

Ice-Confined Synthesis of Stacked Polymer Nanospheres as Osmotic Power Generation Membranes.

Osmotic power extracts electricity from salinity gradients and provides a viable route toward clean energy. To improve the energy conversion efficiency, common strategies rely on fabricating precisely controlled nanopores to meet the requirements of high ionic conductivity and selectivity. We report ion transport through the free-volume networks in stacked polymer nanospheres for osmotic power harvesting. Such nanospheres, composed of coiled poly(acrylic acid) molecules, are synthesized at an ice-liquid interface where they self-assemble into continuous membranes with controlled thicknesses and morphologies. We achieve a rival power density of a few thousand watts per square meter, attributed to the fast and selective ion transport through the nanostructured membranes. The selectivity is further found to originate from the membranes' tunable charging states determined by the association/dissociation equilibrium of the residual groups and the presence of translocation ions. Our work suggests polymer membranes absent of straight-through pores as a new platform for efficient osmotic energy generation.

Small Molecule π-π Stacking Promotes Efficient Photoelectrocatalytic Splitting of Aqueous Hydrogen Production from Polyaniline.

Photoelectrocatalysis efficiency depends on light absorption and the effective use of photogenerated carriers but is often limited by inefficient charge transfer and catalytic surface reactivity. In this study, π-π stacking of polar small molecules on aromatic ring-rich polyaniline (PANI) was carried out to improve its photoelectrocatalytic splitting of water for hydrogen production. Detailed photoelectrochemical experiments and density-functional theory (DFT) calculations show that small molecules of p-aminobenzoic acid (PABA) and PANI have the best π-π stacking (compared to p-toluenesulfonic acid (PTA)), which promotes the separation of carriers on the PANI surface. In addition, the polar effect of the small molecules also improves the reactivity of the PANI surface and also reduces the potential barrier for H2 evolution. The current density of PANI-PABA reached -0.12 mA/cm2 (1.23 V vs. RHE) 2.53 times higher than that of pure PANI in linear voltammetric scanning tests under light. This strategy of introducing polar small molecules into organocatalysts via π-π stacking will provide new ideas for the preparation of efficient organic photoelectrocatalysis.

Non-Volatile Multifunctional Dipole Molecules Enable 19.2% Efficiency for Printable Mesoscopic Perovskite Solar Cells.

Dipole molecules (DMs) show great potential in defect passivation for printable mesoscopic perovskite solar cells (p-MPSCs), although the crystallization process of p-MPSCs is more intricate and challenging than planar perovskite solar cells. In this work, a series of non-volatile multifunctional DMs are employed as additives to enhance the crystallization of perovskites and improve both the power conversion efficiency (PCE) and stability of the devices. This enhancement is achieved by regulating the side groups of benzoic acid molecules with the electron-donating groups such as guanidine (─NH─C(═NH)─NH2), amino (─NH2) and formamidine (─C(═NH)─NH2). DMs form hydrogen bond interactions with the organic cations of perovskite and establish electrostatic interactions with PbI6 4-. The synergistic effect of these interactions suppresses PbI2 formation, enhances perovskite film crystalline quality, reduces perovskite crystal defect density, mitigates non-radiative recombination, and effectively enhances carrier transfer and extraction efficiency. Furthermore, the incorporation of DMs leads to a reconstruction of the perovskite film surface energy level, thereby enhancing hole extraction efficiency at the perovskite/carbon electrode interface. The optimized p-MPSCs achieve a PCE of 19.23%. The unencapsulated device demonstrates promising long-term storage stability, retaining 91% of the original PCE after 1440 h of aging at 40 ±5% relative humidity and 30 ±5°C.

Progress in Tandem Mass Spectrometry Data Analysis for Nucleic Acids.

Mass spectrometry (MS) has become a critical tool in the characterization of covalently modified nucleic acids. Well-developed bottom-up approaches, where nucleic acids are digested with an endonuclease and the resulting oligonucleotides are separated before MS and MS/MS analysis, provide substantial insight into modified nucleotides in biological and synthetic nucleic. Top-down MS presents an alternative approach where the entire nucleic acid molecule is introduced to the mass spectrometer intact and then fragmented by MS/MS. Current top-down MS workflows have incorporated automated, on-line HPLC workflows to enable rapid desalting of nucleic acid samples for facile mass analysis without complication from adduction. Furthermore, optimization of MS/MS parameters utilizing collision, electron, or photon-based activation methods have enabled effective bond cleavage throughout the phosphodiester backbone while limiting secondary fragmentation, allowing characterization of progressively larger (~100 nt) nucleic acids and localization of covalent modifications. Development of software applications to perform automated identification of fragment ions has accelerated the broader adoption of mass spectrometry for analysis of nucleic acids. This review focuses on progress in tandem mass spectrometry for characterization of nucleic acids with particular emphasis on the software tools that have proven critical for advancing the field.

Amino-Acid-Induced Circularly Polarized Luminescence of Octahedral Lanthanide Cage.

Chiral metal organic cage compounds with excellent circularly polarized luminescent performance have broad application prospects in many fields. Herein, two lanthanide complexes with luminescent properties in the form of racemic hexagonal octahedral cages were synthesized using a tri (β-diketone) ligand. Eu6(C21H6F15O6)8(H2O)6 exhibited red light emission with high quantum yields of 61%. Then, we successfully synthesized lanthanide compounds with circularly polarized luminescent activity by chiral induction of the racemic mixture with arginine. The luminescence asymmetry factor was 0.53, and the circularly polarized luminescent merit figure reached 0.323. High-performance circularly polarized luminescent of racemic cage like compound systems have achieved using cheap and readily available chiral amino acid molecules through chiral induction.

Syntheses and structures of two coordination polymers formed by Ni(cyclam)2+ cations and sulfate anions

The asymmetric units of catena-poly[[(1,4,8,11-tetraazacyclotetradecane-κ4 N 1,N 4,N 8,N 11)nickel(II)]-μ2-sulfato-κ2 O 3:O 4], [Ni(SO4)(C10H24N4)] n (I), and catena-poly[[(1,4,8,11-tetraazacyclotetradecane-κ4 N 1,N 4,N 8,N 11)nickel(II)]-μ2-sulfato-κ2 O 3:O 4] hemi[4,4′,4′′,4′′′-(2,2′,4,4′,6,6′-hexamethyl-[1,1′-biphenyl]-3,3′,5,5′-tetrayl)tetrabenzoic acid] nonahydrate], {[Ni(SO4)(C10H24N4)]2·C46H38O8·18H2O} n (II), consist of two crystallographically unique centrosymmetric macrocyclic dications and a sulfate dianion. In II it includes additionally a molecule of the undissociated acid (2,2′,4,4′,6,6′-hexamethyl[1,1′-biphenyl]-3,3′,5,5′-tetrayl)tetra(benzoic acid) located on a crystallographic twofold axis and nine highly disordered water molecules of crystallization. In both compounds, the metal ions are coordinated in the equatorial plane by the four secondary N atoms of the macrocyclic ligand, which adopts the most energetically stable trans-III conformation. Two O atoms of the sulfate anions occupy the trans-axial positions resulting in a slightly tetragonally distorted trans-NiN4O2 octahedral coordination geometry. The crystals of both compounds are composed of parallel coordination polymeric chains running along the [101] and [100] directions in I and II, respectively. The distances between the neighboring metal ions in the chains are significantly different [6.5121 (6) Å in I and 6.0649 (3) Å in II] and this peculiarity is explained by the different spatial directivity of the Ni—O coordination bonds (different S—O—Ni angles). As a result of the C—H...O hydrogen bonds between the methylene groups of the macrocyclic ligands and the non-coordinated O atoms of the sulfate anion, the coordination-polymeric chains in I are arranged in the two-dimensional layers oriented parallel to the (010) and (101) planes, the intersection of which provides the three-dimensional coherence of the crystals. The three-dimensional supramolecular structure of the crystals II is determined by the network of strong hydrogen bonds formed by the carboxylic acid and the non-coordinated O atoms of the sulfate anions.

Managing negative linear compressibility and thermal expansion through steric hindrance: a case study of 1,2-bis(4'-pyridyl)ethane cocrystals.

Multicomponent crystals have great scientific potential because of their amenability to crystal engineering in terms of composition and structure, and hence their properties can be easily modified. More and more research areas are employing the design of multicomponent materials to improve the known or induce novel physicochemical properties of crystals, and recently they have been explored as materials with abnormal pressure behaviour. The cocrystal of 1,2-bis(4'-pyridyl)ethane and fumaric acid (ETYFUM) exhibits a negative linear compressibility behaviour comparable to that of framework and metal-containing materials, but overcomes many of their deficiencies restricting their use. Herein ETYFUM was investigated at low temperature to reveal negative thermal expansion behaviour. Additionally, a cocrystal isostructural with ETYFUM, based on 1,2-bis(4'-pyridyl)ethane and succinic acid (ETYSUC), was exposed to high pressure and low temperature, showing that its behaviour is similar in nature to that of ETYFUM, but significantly differs in the magnitude of both effects. It was revealed that the minor structural difference between the acid molecules does not significantly affect the packing under ambient conditions, but has far-reaching consequences when it comes to the deformation of the structure when exposed to external stimuli.