Noncovalent Intermolecular Interactions Research Articles

Protein and Peptide Based Drug Delivery- A Review

Biologics include vaccines, recombinant proteins, genes, synthetic tissues and viruses, which have emerged from molecular and cellular biology, with respect to unmet clinical needs and expanding indications. Hence it is important at this stage to outline the essential events that have led to the current level of interest in protein and peptide drug delivery systems. Polymers consisting of amino acids that are covalently linked by peptide bonds are known as Proteins and inturn peptides are small proteins composed of few dozen amino acids. Due to large molecular sizes of the proteins ranging from thousands to several millions atomic masses sizes; absorption through the epithelial barriers in the gastrointestinal tract is low. Moreover, proteins are rapidly degraded by digestive enzymes. As the bioavailability by oral route is poor they can be administered by other routes mainly by parenteral (IV, SC, IM) injections. The biological activity of proteins is strongly dependent on their molecular structure i.e 10 structure; the amino acid sequence, which ultimately dictates the non-covalent interactions and the 20i.e alpha helices and beta helices; the periodic spatial arrangement of the polypeptide chain backbone and 30; the 3-dimensional conformation of the whole molecule, including the positions of all amino acid side chains. Some proteins may consist of multiple peptide chains grouped together by non-covalent intermolecular interactions. The arrangement of these subunits relative to each other constitutes the 40structure. An alteration at any level of molecular structure leads to a change or loss of biological activity. The present review focuses on the development of various routes of drug administration, formulation as well as stability aspects of protein and peptide drug delivery system.

Synthesis, Characterization, DFT and Photocatalytic Studies of a New Pyrazine Cadmium(II) Tetrakis(4-methoxy-phenyl)-porphyrin Compound.

This study describes the synthesis, theoretical investigations, and photocatalytic degradational properties of a new (pyrazine)(meso-tetrakis(4-tert-methoxyphenyl)-porphyrinato)-cadmium (II) ([Cd(TMPP)-Pyz]) complex (1). The new penta-coordinated CdII porphyrin complex (1) was characterized by various spectroscopic techniques, including FT-IR, NMR, UV-visible absorption, fluorescence emission, and singlet oxygen, while its molecular structure was studied using single crystal X-ray diffraction. The UV–Vis spectroscopic study highlighted the redshift of the absorption bands after the insertion of the Cd(II) metal ion into the TMPP ring. The co-coordination of the pyrazine axial ligand enhanced this effect. A fluorescence emission spectroscopic study showed a significant blueshift in the Q bands, accompanied by a decrease in the fluorescence emission intensity and quantum yields of Φf = 0.084, Φf = 0.06 and Φf = 0.03 for H2-TMPP free-base porphyrin, [Cd(TMPP)] and [Cd(TMPP)(Pyz)] (1) respectively. Singlet oxygen revealed that the H2-TMPP porphyrin produced the most efficient singlet oxygen quantum yield of (ΦΔ = 0.73) compared to [CdTMPP] (ΦΔ = 0.57) and [Cd(TMPP)(Pyz)] (1) (ΦΔ = 0.13). In the crystal lattice, the [Cd(TMPP)Pyz] was stabilized through non-covalent intermolecular interactions (NCI), such as the hydrogen bonds C-H···N and C-H···Cg. Additionally, crystal explorer software was then utilized to measure the quantitative analysis of the intermolecular interactions in the unit cell of the crystal structure and established that the C-H···π interaction dominated. The Natural bond orbital (NBO) analysis revealed that each molecule is stabilized by hyperconjugation and charge delocalization. As a photocatalyst, the coordination complex 1 showed excellent photocatalytic activity toward the degradation of Levafix Blue CA reactive dye (i.e., dye photo-degradation of 80%).

A Benzene Ring‐Linked Dimethylamino and Borate Ester‐Based Molecule and Organic Crystal: Efficient Dual Room‐Temperature Phosphorescence with Responsive Property

AbstractPure organic crystal of N,N‐di‐methyl‐4‐(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)aniline (DMAB) exhibits efficient room‐temperature phosphorescence (RTP) with an emission maximum at 387 nm and a high phosphorescence efficiency of 35.2%. Significantly, DMAB shows an exceptional photo‐induced ultra‐long RTP (URTP) at 539 nm, which displays an afterglow time of 14 s in air. The two phosphorescent bands are attributed to the monomeric and aggregated RTP of DMAB, respectively. Continuous UV irradiation for ≈1 min can dramatically improve the lifetimes for both of the monomeric and aggregated phosphorescent emissions. The photo‐induced URTP can be spontaneously switched off after standing the crystal in air for 50 min, and this cyclic process has been repeated several times. The molecular packing based on multiple intermolecular noncovalent interactions is adopted in DMAB crystal, which is beneficial to RTP. Upon UV irradiation, the consumption of oxygen in the crystal matrix accounts for the distinctive photo‐induced URTP. Taking advantage of the unique photo/oxygen‐sensitive properties, DMAB crystals have been successfully utilized in oxygen sensing and anticounterfeiting.

Resolving the Conflict between Strength and Toughness in Bioactive Silica-Polymer Hybrid Materials.

Simultaneously improving the strength and toughness of materials is a major challenge. Inorganic-polymer hybrids offer the potential to combine mechanical properties of a stiff inorganic glass with a flexible organic polymer. However, the toughening mechanism at the atomic scale remains largely unknown. Based on combined experimental and molecular dynamics simulation results, we find that the deformation and fracture behavior of hybrids are governed by noncovalent intermolecular interactions between polymer and silica networks rather than the breakage of covalent bonds. We then attempt three methods to improve the balance between strength and toughness of hybrids, namely the total inorganic/organic (I/O) weight ratio, the size of silica nanoparticles, and the ratio of -C-O vs -C-C bonds in the polymer chains. Specifically, for a hybrid with matched silica size and I/O ratio, we demonstrate optimized mechanical properties in terms of strength (1.75 MPa at breakage), degree of elongation at the fracture point (31%), toughness (219 kPa), hardness (1.08 MPa), as well as Young's modulus (3.0 MPa). We also demonstrate that this hybrid material shows excellent biocompatibility and ability to support cell attachment as well as proliferation. This supports the possible application of this material as a strong yet tough bone scaffold material.

Synthesis, covalency parameters, energy calculations and crystal features of acylpyrazolone derived pentavalent Uranyl complex along with DFT and Hirshfeld analysis

A σ-donating acylpyrazolone DMBPMP (4-(3,5-dimethyl benzoyl) 1-phenyl 3-methyl 5-pyrazolone) ligand and its Uranyl acylpyrazolone complex [UO2(DMBPMP)2(EtOH)] were synthesized to analyze the nature of covalency, reactivity, and redox properties. The structure, pentavalent bipyramidal geometry, and complex composition are mainly scrutinized through their single-crystal x-ray crystal data, molar conductivity, gravimetric estimation, FTIR significant vibrations, δ-values of 1H NMR, 13C NMR and TG-DTA plots. The covalency of the Uranyl complex mainly depends on average bond length values on the pentagonal equatorial plane, Uranyl axial bond lengths, stretching frequency values, coordinated solvent on the fifth coordination site, and different aryl group substitution on the first position of the pyrazolone ring; and it can be confirmed through FTIR, single-crystal, and electronic UV–Vis spectral characterization methods. The UV–Vis data was also valuable for identifying n → π*, π → π*, and LMCT transitions and calculating Sinha’s covalency parameters, which shows that the complex can show maximum covalent character in DMSO solvent and covalency decreases in DMSO > DMF > Ethyl acetate > Ethanol > CHCl3 order. DFT calculations were performed to get an excellent correlation and comparison with all experimental values. This correlation and comparision is helpful to identify global index parameters to get an idea of the physical as well as chemical properties of such systems and to confirm the characteristics theoretically by HOMO-LUMO energy gap, theoretical vibrations, natural electronic configuration, and NBO charges. The Hirshfeld surface analysis was also carried out to identify the crystal strength through interaction energies and energy frameworks in the ligand and intermolecular non-covalent surface interactions with fingerprint plot details in both ligand and complex. Electro-chemical analysis in CV-DPV plots provides information on the redox properties of uranyl moiety.

Optimization of the r2SCAN-3c Composite Electronic-Structure Method for Use with Slater-Type Orbital Basis Sets.

The “Swiss army knife” composite density functional electronic-structure method r2SCAN-3c (J. Chem. Phys.2021, 154, 064103) is extended and optimized for the use with Slater-type orbital basis sets. The meta generalized-gradient approximation (meta-GGA) functional r2SCAN by Furness et al. is combined with a tailor-made polarized triple-ζ Slater-type atomic orbital (STO) basis set (mTZ2P), the semiclassical London dispersion correction (D4), and a geometrical counterpoise (gCP) correction. Relativistic effects are treated explicitly with the scalar-relativistic zeroth-order regular approximation (SR-ZORA). The performance of the new implementation is assessed on eight geometry and 74 energy benchmark sets, including the extensive GMTKN55 database as well as recent sets such as ROST61 and IONPI19. In geometry optimizations, the STO-based r2SCAN-3c is either on par with or more accurate than the hybrid density functional approximation M06-2X-D3(0)/TZP. In energy calculations, the overall accuracy is similar to the original implementation of r2SCAN-3c with Gaussian-type atomic orbitals (GTO), but basic properties, intermolecular noncovalent interactions, and barrier heights are better described with the STO approach, resulting in a lower weighted mean absolute deviation (WTMAD-2(STO) = 7.15 vs 7.50 kcal mol–1 with the original method) for the GMTKN55 database. The STO-optimized r2SCAN-3c outperforms many conventional hybrid/QZ approaches in most common applications at a fraction of their cost. The reliable, robust, and accurate r2SCAN-3c implementation with STOs is a promising alternative to the original implementation with GTOs and can be generally used for a broad field of quantum chemical problems.

The combination of terahertz spectroscopy and density functional theory for vibrational modes and weak interactions analysis of vanillin derivatives

Three vanillin derivatives, including methyl vanillin, ethyl vanillin, and vanillyl alcohol were investigated in the range of 0.4–2.0 THz by terahertz time-domain spectroscopy (THz-TDS) and density functional theory (DFT). Vibrational mode automatic relevance determination (VMARD) method was introduced to assign the absorption peaks to the contribution ratio of corresponding vibrational modes, and VMARD revealed the dihedral angle torsion was the primary vibrational mode. Simultaneously, through independent gradient model based on Hirshfeld partition of molecular density (IGMH) method, van der Waals interaction was ascertained to be dominant weak noncovalent intermolecular interaction. This research, combining THz-TDS and the above-mentioned methods, elucidates the principle of material performance differences with structural analogs in the terahertz frequency band.

Pillararenes as Versatile Building Blocks for Fluorescent Materials

ConspectusFluorescent materials have received more and more attention in the past few decades because of their great potentials in the fields of luminescent devices, sensing, data storage, bioimaging, and other optical applications. Fluorescent materials comprising organic molecules are of broad interest owing to their highly tunable emission. Initial studies on organic fluorescent materials were mainly focused on the design and covalent modification of fluorophores in order to improve their photophysical properties at the molecular level, whereas in recent decades, many studies have revealed that the intermolecular or intramolecular noncovalent interactions also play a crucial role in luminescence. For example, the modulation of noncovalent interactions in aggregates and self-assemblies was proven to be capable of adjusting aggregation-induced emission (AIE)-active fluorophores by the restriction of intramolecular motions (RIM). In addition, in the crystalline state, intermolecular noncovalent interactions are able to promote phosphorescence by decreasing nonradiative decays.Introducing supramolecular macrocycles into organic fluorescent materials is an intriguing prospect because multiple noncovalent interactions are incorporated. On one hand, the photophysical properties of fluorophores can be changed upon inclusion within the macrocycles, providing unforeseen luminescence. On the other hand, the dynamic and reversible features of host–guest recognition endow the materials with controllability and stimuli-responsiveness, which is beneficial to the fabrication of smart materials. Among numerous supramolecular macrocycles, pillararenes are promising candidates that can be included in fluorescent materials. The advantages of pillararenes are their easy functionalization and planar chirality. After modification with proper substituents, pillararene derivatives possess high solubility and stability in both organic and aqueous media, and reversible guest binding remains. Such features make pillararenes versatile hosts in different environments. Additionally, pillararenes are planar chiral, and the interconversion between enantiomers can be adjusted with different-sized substituents and external stimuli, which are favorable to the construction of chiroptical materials.In this Account, we summarize research progress in the field of pillararene-based luminescent materials, which mainly includes the contributions made by our group. Using pillararenes as building blocks can facilitate the fabrication of high-performance fluorescent materials, in solution or the solid state, with different functions and mechanisms. Therefore, we categorize pillararene-based luminescent materials as those in solution or in the solid state. The applications and the advantages of pillararenes are discussed in detail. For example, in the solid state, pillararene-based host–guest complexation is capable of minimizing the aggregation-caused quenching (ACQ) of fluorophores. This broadens the application of fluorophores in crystalline materials. In solution, the host–guest complexes of pillararenes and fluorophores can self-assemble into well-defined nanostructures, which not only adjust the photophysical properties but also enable functions such as bioimaging. The remaining challenges and future perspectives are outlined at the end. It is expected that this Account will inspire new researchers in different fields and offer new opportunities for the construction of novel luminescent materials with pillararenes and other macrocycles.

Hierarchical graphite oxide decorated UiO-66 for ultrahigh adsorption of dye with synergistic effect of ultrasonication: Experimental and density functional theory study

Indiscriminate disposal of azodyes demands the development of potential strategies for water treatment. Composites with tuned structural and functional properties, synthesized by amalgamation of 2D carbon materials with MOFs, emerges as a new generation adsorbents.Accordingly, our study focused on the synthesis of graphite oxide decorated UiO-66 MOF and its performance evaluation in ultrasonication assisted adsorptive removal of toxic Congo red dye from aqueous solution. The incorporation of GO tunes the microporous MOF to a hierarchical mesoporous/microporous structure. Theoretical analysis using density functional theory (DFT) was performed to predict the adsorption behaviour.The key finding which makes our study outstanding is the ultrahigh adsorption capacity (Qm − 1250 mg/g) of the synthesized composite, which is much higher than pure UiO-66, GO, and other reported adsorbents. The synergistic effect of the increased mesopore volume and availability of functional groups upon GO incorporation in the MOF improves the adsorption capacity. Adsorption occurs due to long-range intermolecular covalent and noncovalent interactions. The superior dye removal efficiency of the synthesized adsorbent along with good regeneration characteristics makes it a promising material for contaminants removal from aqueous solutions.

Crystal Forms of the Antihypertensive Drug Irbesartan: A Crystallographic, Spectroscopic, and Hirshfeld Surface Analysis Investigation.

The design of new pharmaceutical solids with improved physical and chemical properties can be reached through in-detail knowledge of the noncovalent intermolecular interactions between the molecules in the context of crystal packing. Although crystallization from solutions is well-known for obtaining new solids, the effect of some variables on crystallization is not yet thoroughly understood. Among these variables, solvents are noteworthy. In this context, the present study aimed to investigate the effect of ethanol (EtOH), acetonitrile (MeCN), and acetone (ACTN) on obtaining irbesartan (IBS) crystal forms with 2,3-dibromosuccinic acid. Crystal structures were solved by single-crystal diffraction, and the intermolecular interactions were analyzed using the Hirshfeld surfaces analysis. The characterization of physicochemical properties was carried out by powder X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), thermal analysis, and solution-state NMR techniques. Two different IBS salts were obtained, one from MeCN and ACTN (compound 1) and a different one from EtOH (compound 2). The experimental results were in agreement with the findings obtained through quantum mechanics continuum solvation models. Compound 1 crystallized as a monoclinic system P21/c, whereas compound 2 in a triclinic system P1̅. In both structures, a net of strong hydrogen bonds is present, and their existence was confirmed by the FT-IR results. In addition, the IBS cation acts as a H-bond donor through the N1 and N6 nitrogen atoms which interact with the bromide anion and the water molecule O1W in compound 1. Meanwhile, N1 and N6 nitrogen atoms interact with the oxygen atoms provided by two symmetry-related 2,3-dibromo succinate anions in compound 2. Solution-state NMR data agreed with the protonation of the imidazolone ring in the crystal structure of compound 1. Both salts presented a different thermal behavior not only in melting temperature but also in thermal stability.

Intermolecular Vibration Energy Transfer Process in Two CL-20-Based Cocrystals Theoretically Revealed by Two-Dimensional Infrared Spectra.

Inspired by the recent cocrystallization and theory of energetic materials, we theoretically investigated the intermolecular vibrational energy transfer process and the non-covalent intermolecular interactions between explosive compounds. The intermolecular interactions between 2,4,6-trinitrotoluene (TNT) and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and between 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) and CL-20 were studied using calculated two-dimensional infrared (2D IR) spectra and the independent gradient model based on the Hirshfeld partition (IGMH) method, respectively. Based on the comparison of the theoretical infrared spectra and optimized geometries with experimental results, the theoretical models can effectively reproduce the experimental geometries. By analyzing cross-peaks in the 2D IR spectra of TNT/CL-20, the intermolecular vibrational energy transfer process between TNT and CL-20 was calculated, and the conclusion was made that the vibrational energy transfer process between CL-20 and TNTII (TNTIII) is relatively slower than between CL-20 and TNTI. As the vibration energy transfer is the bridge of the intermolecular interactions, the weak intermolecular interactions were visualized using the IGMH method, and the results demonstrate that the intermolecular non-covalent interactions of TNT/CL-20 include van der Waals (vdW) interactions and hydrogen bonds, while the intermolecular non-covalent interactions of HMX/CL-20 are mainly comprised of vdW interactions. Further, we determined that the intermolecular interaction can stabilize the trigger bond in TNT/CL-20 and HMX/CL-20 based on Mayer bond order density, and stronger intermolecular interactions generally indicate lower impact sensitivity of energetic materials. We believe that the results obtained in this work are important for a better understanding of the cocrystal mechanism and its application in the field of energetic materials.

Impact of Intermolecular Non-Covalent Interactions in a CuI 8 PdII 1 Discrete Assembly: Conformers' Geometries and Stimuli-Sensitive Luminescence Properties.

A new highly solid-state luminescent phase of a previously reported weakly luminescent CuI 8 PdII 1 dicationic assembly is reported revealing the high geometrical versatility of this moiety that importantly alters its luminescent properties. This very minor new species Bc is based on a different conformer scaffold than the one encountered in the previously reported Bo form and, essentially differs from Bo by displaying shorter CuI -CuI intermetallic distances. DFT calculations allow concluding that the predominance in the solid-state of the weakly luminescent and less stable Bo phase is due to the extra stability induced by a larger number of intermolecular non-covalent π-CH interactions in its crystalline packing and not by the intrinsic stability of the CuI 8 PdII 1 dicationic moiety. Calculations also revealed that a more stable conformation Bcalc is expected in vacuum, which bears a different distribution of CuI -CuI intermetallic distances than the dications in Bo and Bc phases. Taking into account that the geometrical alterations are associated to drastic changes of luminescence properties, this confer to the CuI 8 PdII 1 assembly high potentiality as stimuli-sensitive luminescent materials. Indeed, by applying mechanical or thermal stress to samples of Bo phase, new phases Bg and Bm , respectively, were obtained. Alterations of the solid-state photophysical properties of these new species compared to those recorded for Bo are reported together with a combined experimental and computed study of the structures/properties relationships observed in these phases.

A thiomethyl-substituted imidazolyl imine functionalized copper(II) complex: synthesis, structural characterization, phenoxazinone synthase mimics and biological activities

A cis-dichloro copper(II) complex with a novel tridentate thiomethyl substituted imidazole based Schiff base ligand L, obtained from 2-methylthioaniline and 2-imidazolecarboxaldehyde, has been synthesized and characterized by spectroscopic methods and X-ray crystallography. The crystal structure of the complex shows a distorted square-pyramidal environment around the copper(II) centre, coordinated by the tridentate ligand L and two cis-chloride ligands (one axial and another equatorial). The supramolecular framework, connected through several intermolecular noncovalent interactions in the crystal structure, has been investigated in detail. The complex effectively shows phenoxazinone synthase-like activity (aerial oxidation of 2-aminophenol to 2-amino-phenoxazine-3-one) under ambient conditions with a high turnover number of 1.92 × 104 h−1. Further, the antimicrobial activity of the copper(II) complex was examined against E. coli, Staphylococcus aureus and K. pneumoniae clinical microbial cultures, which imply its significant bactericidal property compared to the standard antibiotic agent ciprofloxacin. In addition, the anticancer activity of the copper(II) complex was tested against the human colorectal adenocarcinoma (HT-29) cancerous cell line and it shows notable activity with an IC50 value of 125 μg mL−1.

Evaluation of PEG and sugars consolidated fragile waterlogged archaeological wood using nanoindentation and ATR-FTIR imaging

Waterlogged archaeological wood (WAW) undergoes biological deterioration during long-term immersion in microorganisms-rich aquatic environments. The consolidants are commonly applied to avoid wood deformation upon drying. It is urgent to develop a systematic evaluation method to study the impact of the consolidant distribution and the intermolecular interactions among consolidants and cell wall components on the improvement of wood mechanical traits. In order to evaluate the effect of consolidant distribution and intermolecular interactions between consolidants and cell wall components on the mechanical improvement, herein, we proposed in situ analysis methods involving Nanoindentation (NI) technology (without prior embedding) along with attenuated total reflection Fourier transform infrared imaging (ATR-FTIR imaging). Moreover, PEG, sucralose, and trehalose were chosen as representative consolidants to treat moderately deteriorated WAW because of their different molecular weights and different hydrophilic groups. Results showed that the mechanical improvement in consolidated WAW was significant. The elastic modulus and hardness of WAW after consolidation with PEG, sucralose and trehalose increased, with improvements of 15.3% and 34.8%, 43.9% and 49.5%, 31.9% and 6.4%, respectively, compared to untreated WAW. All three consolidants were found under scanning electron microscopy (SEM) to have filled wood cell lumens and mesopores in cell walls to different extents. ATR-FTIR imaging and thermogravimetric analysis (TGA) results further indicated that consolidants partly penetrated the wood cell walls. PEG was more concentrated near the fiber lumina. In addition, TGA revealed that the relative contents of PEG and trehalose in consolidated archaeological woods were 54.0% and 39.8%, and the maximum decomposition temperature (Td) of consolidated WAW all differed from the untreated WAW, which suggested non-covalent intermolecular interactions were probably presented between consolidants and WAW cell wall components.

Arene-ruthenium(II) complexes with tetracyclic oxime derivatives: synthesis, structure and antiproliferative activity against human breast cancer cells

Six new arene-ruthenium(II) complexes containing two different η6-arene ligands – benzene and hexamethylbenzene, with indenoquinoxalinone oxime analogues (11H-indeno[1,2-b]quinoxalin-11-one oxime, 6H-indeno[1,2-b]pyrido[3,2-e]pyrazin-6-one oxime and 6–(hydroxyimino)indolo[2,1-b]quinazolin-12(6H)-one oxime (tryptanthrin-6-oxime)) as N,N’- chelating ligands are reported. The complexes were characterized by elemental analysis, IR, UV–VIS, 1H and 13C NMR spectroscopy and by single-crystal X-ray structure analysis. Complexes adopt a half-sandwich «piano-stool» geometry with oxime ligands in anionic form, the ruthenium(II) center coordinates one arene, one N,N-bidentate oximate and one chloride ligand. The computational analysis of non-covalent intermolecular interactions revealed weak attraction between the oxime oxygen atoms and the nearest hydrogen atoms of the oxime and the arene ligands. The cytotoxic activity of the complexes was evaluated against human breast cancer cell line MCF-7 and cisplatin-resistant human breast cancer cell line MCF-7CR as well as non-cancerous human breast epithelial cell line MCF10A. The cytotoxicity tests show micromolar IC50 values and tryptanthrin-6-oxime hexamethylbenzene-ruthenium(II) complex was found to exhibit the best antiproliferative activity among the studied compounds against the MCF-7 and MCF-7CR cell lines (IC50 9.0 ± 4.4 and 8.9 ± 1.5 µM, respectively).

Experimental and computational studies on copper(II) Schiff base complex derived from 4-acetyl-3-methyl-1-phenyl-2-pyrazolin-5-one

A new tetradentate N2O2 type Schiff-base ligand (H2L) was synthesized from the condensation of 4-acetyl-3-methyl-1-phenyl-2-pyrazoline-5-one with 2,2-dimethyl-1,3-propanediamine. The corresponding Cu(II) complex (CuL) was also synthesized. The ligand and the complex were characterized by FTIR and UV-Vis spectroscopy and elemental analysis. 1H- and 13C NMR spectra of the ligand and X-ray crystal structure of the complex were obtained. The main non-covalent intermolecular interactions were studied by Hirshfeld surface analysis and finger print plots. Due to the different structural possibility including imine‐one, amine‐ol, and amine-one forms for H2L compound, their conformational and geometrical aspects were investigated computationally by DFT/ M06-2X-6-311+G(d,p) methods. The computational results suggested that the amine-one is the most favorable tautomeric form.

Non-Covalent Interactions in Organic, Organometallic, and Inorganic Supramolecular Systems Relevant for Medicine, Materials Science, and Catalysis

The structure, fundamental properties, and reactivity of chemical systems at various hierarchical levels of organization of matter is the paradigm of chemistry. A qualitative and quantitative description of various intermolecular and intramolecular non-covalent interactions in chemical systems is the main tool for supramolecular design and the driving force of smart prediction of kinetic and thermodynamic parameters of chemical reactions. This perspective is dedicated to highlighting the recent progress of our research group in the investigation of various non-covalent contacts in organic, organometallic, and inorganic chemical systems relevant for medicine, materials science, and catalysis. This research is interdisciplinary in nature and lies at the intersection of computer modeling with such natural science disciplines as chemistry, physics, crystallography, biology, and medicine, as well as directly related to materials science and nanotechnology.

Gel Materials with Rubber‐Rubbing‐Chromic Luminescence: A Portable Tool for On‐Spot Composing Highly Encrypted Information

AbstractGels generally comprise different intermolecular noncovalent interactions for sustaining self‐assembled structures, which renders them sensitive to external stimuli, while simultaneously sacrificing their stimuli‐responsive selectivity. Supramolecular and polymeric gels are constructed here by the coassembly of a dipyridinil phenol as the crosslinker with the gelator counterparts. In these systems, an ordered multiple H‐bonded network facilitates a proton transferred tautomerization caused by the triboelectric effect of rubber rubbing, resulting in an unprecedented rubber‐rubbing‐chromic luminescence. This process is efficient and highly selective, as the friction with other materials fails to cause such a phenomenon. This results in a unique negative charge (−117 nC J−1, exactly provided by the triboelectric effect of the rubber material) inducing the topochemical tautomerization at the gel level. Moreover, the polymeric gels exhibit superior mechanical properties and can be processed into a chalk‐like portable tool for writing. The composed luminescent information is also sensitive to rubber rubbing, featuring considerable practicability in on‐spot information encryption and anticounterfeiting.

Heteroleptic Pd(II) and Pt(II) Complexes with Redox-Active Ligands: Synthesis, Structure, and Multimodal Anticancer Mechanism.

A series of heteroleptic square-planar Pt and Pd complexes with bis(diisopropylphenyl) iminoacenaphtene (dpp-Bian) and Cl, 1,3-dithia-2-thione-4,5-dithiolate (dmit), or 1,3-dithia-2-thione-4,5-diselenolate (dsit) ligands have been prepared and characterized by spectroscopic techniques, elemental analysis, X-ray diffraction analysis, and cyclic voltammetry (CV). The intermolecular noncovalent interactions in the crystal structures were assessed by density functional theory (DFT) calculations. The anticancer activity of Pd complexes in breast cancer cell lines was limited by their solubility. Pd(dpp-Bian) complexes with dmit and dsit ligands as well as an uncoordinated dpp-Bian ligand were devoid of cytotoxicity, while the [Pd(dpp-Bian)Cl2] complex was cytotoxic. On the contrary, all Pt(dpp-Bian) complexes demonstrated anticancer activity in a low micromolar concentration range, which was 8-20 times higher than the activity of cisplatin, and up to 2.5-fold selectivity toward cancer cells over healthy fibroblasts. The presence of a redox-active dpp-Bian ligand in Pt and Pd complexes resulted in the induction of reactive oxygen species (ROS) in cancer cells. In addition, these complexes were able to intercalate into DNA, indicating the dual mechanism of action.

Augmented Self-Association by Electrostatic Forces in Thienopyrrole-Fused Thiadiazoles that Contain an Ester instead of an Ether Linker.

During the self-assembly of π-conjugated molecules, linkers and substituents can potentially add supportive noncovalent intermolecular interactions to π-stacking interactions. Here, we report the self-assembly behavior of thienopyrrole-fused thiadiazole (TPT) fluorescent dyes that possess ester or ether linkers and dodecyloxy side chains in solution and the condensed phase. A comparison of the self-association behavior of the ester- and ether-bridged compounds in solution using detailed UV-vis, fluorescence, and NMR spectroscopic studies revealed that the subtle replacement of the ether linkers by ester linkers leads to a distinct increase in the association constant (ca. 3-4 fold) and the enthalpic contribution (ca. 3 kcal mol-1 ). Theoretical calculations suggest that the ester linkers, which are in close proximity to one another due to the π-stacking interactions, induce attractive electrostatic forces and augment self-association. The self-assembly of TPT dyes into well-defined 1D clusters with high aspect ratios was observed, and their morphologies and crystallinity were investigated using SEM and X-ray diffraction analyses. TPTs with ester linkers exhibit a columnar liquid crystalline mesophase in the condensed phase.