Weak Intermolecular Interactions Research Articles

An elastic organic crystal with multilevel stimuli-responsive room temperature phosphorescence

•Elastic organic RTP crystal with multilevel stimuli responsiveness was first reported •Highest RTP quantum yield of 25.1% was recorded in elastic organic RTP crystal •Modulation of RTP was realized via the transition of excited state conformation •RTP single to double emission under external stimuli in single-component system In this work, we report a series of single-component molecules crystals named dialkyl 4,4′-oxalyldibenzoate (n-BZ) with both efficient room temperature phosphorescence (RTP) emission, multilevel stimuli responsiveness, and elasticity or flexibility. The crystalline n-BZ will change from original RTP single emission to RTP dual emission after grinding or thermal annealing (TA). Interestingly, the emission wavelength difference between the RTP dual-emission peaks after grinding or TA reaches 82 nm with emission color changes from cyan blue to orange. In addition, to our knowledge, the largest RTP quantum yield of 25.1% (6-BZ) has been achieved as the highest recorded for organic RTP elastic crystals. Through a series of experiments and theoretical calculations, we demonstrate that the multilevel stimuli responsiveness of n-BZ originates from the transition of excited state conformation and its elasticity from many weak intermolecular interactions, which will provide a molecular design and construction strategy for organic stimuli-responsive RTP materials. In this work, we report a series of single-component molecules crystals named dialkyl 4,4′-oxalyldibenzoate (n-BZ) with both efficient room temperature phosphorescence (RTP) emission, multilevel stimuli responsiveness, and elasticity or flexibility. The crystalline n-BZ will change from original RTP single emission to RTP dual emission after grinding or thermal annealing (TA). Interestingly, the emission wavelength difference between the RTP dual-emission peaks after grinding or TA reaches 82 nm with emission color changes from cyan blue to orange. In addition, to our knowledge, the largest RTP quantum yield of 25.1% (6-BZ) has been achieved as the highest recorded for organic RTP elastic crystals. Through a series of experiments and theoretical calculations, we demonstrate that the multilevel stimuli responsiveness of n-BZ originates from the transition of excited state conformation and its elasticity from many weak intermolecular interactions, which will provide a molecular design and construction strategy for organic stimuli-responsive RTP materials.

In vitro and in silico assessment of endocrine disrupting effects of food contaminants through pregnane X receptor.

As a promiscuous xenobiotic receptor, pregnane X receptor (PXR) has been confirmed to participate in numerous physiological process. In addition to the conventional estrogen/androgen receptor, PXR also serves as an alternative target for environmental chemical contaminants. In this work, the PXR-mediated endocrine disrupting effects of typical food contaminants were explored. Firstly, the time-resolved fluorescence resonance energy transfer assays confirmed the PXR binding affinities of 2,2',4,4',5,5'-hexachlorobiphenyl, bis(2-ethylhexyl) phthalate, dibutyl phthalate, chlorpyrifos, bisphenol A, and zearalenone, with IC50 values ranging from 1.88 to 4284.00nM. Then their PXR agonist activities were assessed by PXR-mediated CYP3A4 reporter gene assays. Subsequently, the regulation of gene expressions of PXR and its targets CYP3A4, UGT1A1, and MDR1 by these compounds was further investigated. Intriguingly, all the tested compounds interfered with these gene expressions, confirming their endocrine disrupting effects via PXR-mediated signaling. The compound-PXR-LBD binding interactions were explored by molecular docking and molecular dynamics simulations to unravel the structural basis of their PXR binding capacities. The weak intermolecular interactions are key players in stabilizing these compound-PXR-LBD complexes. During the simulation process, 2,2',4,4',5,5'-hexachlorobiphenyl remained stable while the other 5 compounds underwent relatively severe disturbances. In conclusion, these food contaminants might exhibit endocrine disrupting effects via PXR.

Physico-Chemical Characterization, DFT Modeling and Biological Activities of a New Zn (II) Complex Containing Melamine as a Template

Single crystals of a new organic–inorganic hybrid compound (C3H7N6)2[ZnCl4]·H2O was synthesized and characterized by X-ray diffraction at room temperature, FT-IR and FT-Raman spectroscopies, optical absorption and photoluminescence behavior. The title compound belongs to the triclinic space group P1¯, and in the crystal structure, the inorganic layers are built from tetrachloridozincate anions [ZnCl4]2− and free water molecules, linked together by O–H···Cl hydrogen bonds and halogen···halogen interactions. In addition, Hirshfeld surfaces and 2D fingerprint plots estimate the weak intermolecular interactions accountable for the generation of crystal packing. The optimized geometry, vibrational frequencies and various thermodynamic parameters of the title compound calculated using density functional theory (DFT) methods are in agreement with the experimental values. The theoretical calculations were performed using the DFT method at WB97XD/Lanl2dz basis set levels and we discussed topological analysis of atoms in molecules (AIM) at the BCP point. A detailed interpretation of the IR and Raman spectra were reported. Additionally, the simulated spectrum satisfactorily coincided with the experimental UV-Visible spectrum. A wide band gap exceeding 4 eV of the synthesized compound was recorded. The photoluminescence (PL) was characterized through two bands successively at 453 and 477 nm. Ultimately, antimicrobial activity and enzymatic inhibition assays of the complex were also investigated through microbial strains, agar diffusion method, minimum inhibitory concentration (MIC) determination, lipase and phospholipase A2 inhibition.

Preparation and Biomedical Applications of Cucurbit[n]uril-Based Supramolecular Hydrogels.

The cucurbit[n]uril supramolecular hydrogels are driven by weak intermolecular interactions, of which exhibit good stimuli responsiveness and excellent self-healing properties. According to the composition of the gelling factor, supramolecular hydrogels comprise Q[n]-cross-linked small molecules and Q[n]-cross-linked polymers. According to different driving forces, hydrogels are driven by the outer-surface interaction, the host-guest inclusion interaction, and the host-guest exclusion interaction. Host-guest interactions are widely used in the construction of self-healing hydrogels, which can spontaneously recover after being damaged, thereby prolonging their service life. The smart Q[n]s-based supramolecular hydrogel composed is a kind of adjustable and low-toxicity soft material. By designing the structure of the hydrogel or modifying the fluorescent properties, etc., it can be widely used in biomedicine. In this review, we mainly focus on the preparation of Q[n]-based hydrogels and their biomedical applications including cell encapsulation for biocatalysis, biosensors for high sensitivity, 3D printing for potential tissue engineering, drug release for sustained delivery, and interfacial adhesion for self-healing materials. In addition, we also presented the current challenges and prospects in this field.

Interfacial thermal resistance calculations for weak solid–liquid atom interactions using equilibrium molecular dynamics

ABSTRACT This study investigates the use of equilibrium molecular dynamics (EMD) simulations for determining interfacial thermal resistance (ITR) at solid-liquid interfaces. The Green-Kubo theorem is typically used for this purpose, but it may not be suitable for hydrophobic conditions where the interaction between liquid and solid atoms is weak. Two EMD simulation methods were used to calculate ITR at interfaces under different wetting conditions: one using instantaneous temperature differences and the other using instantaneous heat flux. The data derived from the EMD simulation using instantaneous temperature difference could not converge due to weak intermolecular interactions, leading to inaccurate ITR calculations. To address this issue, a method for calculating ITR in the frequency domain is proposed. Results showed that both EMD methods produced different results from non-equilibrium molecular dynamics (NEMD), with the ITR of EMD using instantaneous heat flux being higher than that of NEMD, while the ITR of EMD using instantaneous temperature was lower, and in good agreement with NEMD. Overall, this study highlights the limitations of using EMD simulations for calculating ITR at solid-liquid interfaces in hydrophobic conditions and proposes a new method for improving accuracy in these situations.

Systematic Study of Solid-State Fluorescence and Molecular Packing of Methoxy-trans-Stilbene Derivatives, Exploration of Weak Intermolecular Interactions Based on Hirshfeld Surface Analysis

In recent years, fluorescent compounds that emit efficiently in the solid state have become particularly interesting, especially those that are easily prepared and inexpensive. Hence, exploring the photophysical properties of stilbene derivatives, supported by a detailed analysis of molecular packing obtained from single-crystal X-ray diffraction data, is a relevant area of research. A complete understanding of the interactions to determine the molecular packing in the crystal lattice and their effect on the material's physicochemical properties is essential to tune various properties effectively. In the present study, we examined a series of methoxy-trans-stilbene analogs with substitution pattern-dependent fluorescence lifetimes between 0.82 and 3.46 ns and a moderate-to-high fluorescence quantum yield of 0.07-0.69. The relationships between the solid-state fluorescence properties and the structure of studied compounds based on X-ray analysis were investigated. As a result, the QSPR model was developed using PLSR (Partial Least Squares Regression). Decomposition of the Hirshfeld surfaces (calculated based on the arrangement of molecules in the crystal lattice) revealed the various types of weak intermolecular interactions that occurred in the crystal lattice. The obtained data, in combination with global reactivity descriptors calculated using HOMO and LUMO energy values, were used as explanatory variables. The developed model was characterized by good validation metrics (RMSECAL = 0.017, RMSECV = 0.029, R2CAL = 0.989, and R2CV = 0.968) and indicated that the solid-state fluorescence quantum yield of methoxy-trans-stilbene derivatives was mainly dependent on weak intermolecular C…C contacts corresponding to π-π stacking and C…O/O…C interactions. To a lesser extent and inversely proportional, the fluorescence quantum yield was affected by the interactions of the type O…H/H…O and H…H and the electrophilicity of the molecule.

In situ orderly self-assembly strategy affording NIR-II-J-aggregates for in vivo imaging and surgical navigation

J-aggregation, an effective strategy to extend wavelength, has been considered as a promising method for constructing NIR-II fluorophores. However, due to weak intermolecular interactions, conventional J-aggregates are easily decomposed into monomers in the biological environment. Although adding external carriers could help conventional J-aggregates stabilize, such methods still suffer from high-concentration dependence and are unsuitable for activatable probes design. Besides, these carriers-assisted nanoparticles are risky of disassembly in lipophilic environment. Herein, by fusing the precipitated dye (HPQ) which has orderly self-assembly structure, onto simple hemi-cyanine conjugated system, we construct a series of activatable, high-stability NIR-II-J-aggregates which overcome conventional J-aggregates carrier’s dependence and could in situ self-assembly in vivo. Further, we employ the NIR-II-J-aggregates probe HPQ-Zzh-B to achieve the long-term in situ imaging of tumor and precise tumor resection by NIR-II imaging navigation for reducing lung metastasis. We believe this strategy will advance the development of controllable NIR-II-J-aggregates and precise bioimaging in vivo.

Unraveling Weak Interaction of Kinematic Viscosity of Fatty Acid Methyl Esters in Natural Ester Insulating Oils

Natural ester insulating oil has become a good substitute for mineral insulating oil due to its characteristics of renewability, easy degradation, low carbon emission, and high fire safety. However, the high kinematic viscosity of natural ester insulating oil not only affects the heat dissipation and heat transfer of the transformers but also seriously restricts its safe promotion and application in transformers in cold regions. In this article, in order to explore the influence mechanism of the kinematic viscosity of natural fatty acid methyl ester (FAME), insulating oil molecules from the microscopic scale of weak intermolecular interaction, the electrostatic potential (ESP), van der Waals (vdW) potential, and average local ionization energy (ALIE) of four FAME molecules are analyzed, respectively. The computed results demonstrate that the C=C double bonds in the four FAME molecules weaken the intermolecular electrostatic interaction and vdW interaction, and the weakening effect increases with the increase of the number of the C=C double bonds. This may be for this reason that the C=C double bond reduces the kinematic viscosity. This study can provide theoretical guidance and a basis for quantitative analysis and comparison for the improvement of the kinematic viscosity of natural ester insulating oil, lubricating oil, and biodiesel.

Trapped yet Free inside the Tube: Supramolecular Chemistry of Molecular Peapods

Abstract Supramolecular composites of carbon nanotubes and trapped fullerenes are known as peapods, and the structures of the “peapods” have been diversified by trapping many other entities in the cylindrical nanospaces. By using the molecular segments of carbon nanotubes, we have explored the supramolecular chemistries of discrete molecular peapods exhibiting atomically precise structures. In this Account, the supramolecular molecular peapod chemistry investigated in our group is reviewed. Although the peapods are assembled by weak intermolecular interactions such as van der Waals interactions and CH-π hydrogen bonds, the association force can be so tight that it results in an association constant of 1012 M−1 in solution owing to the presence of multiple interactions. These multiple interactions also enable dynamic motions of the tightly trapped guests either in the solution phase or in the solid state. The solid-state dynamic motions of the molecular peapods are particularly anomalous and can take place with ultrafast rotational frequencies in the inertial regime.

Data-Driven Prediction of Janus/Core-Shell Morphology in Polymer Particles: A Machine-Learning Approach.

The majority of research on Janus particles prepared by solvent evaporation-induced phase separation technique uses models based on interfacial tension or free energy to predict Janus/core-shell morphology. Data-driven predictions, in contrast, utilize multiple samples to identify patterns and outliers. Using machine-learning algorithms and explainable artificial intelligence (XAI) analysis, we developed a model based on a 200-instance data set to predict particle morphology. As model features, simplified molecular input line entry system syntax identifies explanatory variables, including cohesive energy density, molar volume, the Flory-Huggins interaction parameter of polymers, and the solvent solubility parameter. Our most accurate ensemble classifiers predict morphology with an accuracy of 90%. In addition, we employ innovative XAI tools to interpret system behavior, suggesting phase-separated morphology to be most affected by solvent solubility, polymer cohesive energy difference, and blend composition. While polymers with cohesive energy densities above a certain threshold favor the core-shell structure, systems with weak intermolecular interactions favor the Janus structure. The correlation between molar volume and morphology suggests that increasing the size of polymer repeating units favors Janus particles. Additionally, the Janus structure is preferred when the Flory-Huggins interaction parameter exceeds 0.4. XAI analysis introduces feature values that generate the thermodynamically low driving force of phase separation, resulting in kinetically stable morphologies as opposed to thermodynamically stable ones. The Shapley plots of this study also reveal novel methods for creating Janus or core-shell particles based on solvent evaporation-induced phase separation by selecting feature values that strongly favor a given morphology.

Discrete Molecular Aggregates Based on ZnII and SbIII/V Ions Displaying Efficient Antibacterial and Antioxidant Properties.

The reactions of [Zn3Cl2(3,5-Me2PzH)4(t-BuPO3)2] with organostibonic acid in varying reaction conditions have been investigated. Single-crystal X-ray diffraction studies reveal the formation of [Zn2(p-ClC6H4Sb)2(O)2(OCH3)2(t-BuPO3)3(py)2] (1), [Zn2(p-ClC6H4SbV)4(SbIII)2(O)8(t-BuPO3H)4(t-BuPO3)2(py)2Cl2] (2), and [Zn2(RSb)4(O)4(OCH3)4(t-BuPO3)4(py)2], where R = p-ClC6H4 (3) and R = p-iPrC6H4 (4), respectively. Interestingly, in the synthesis of 2, complete dearylation of organoantimony moieties followed by C-F bond formation, a reduction from Sb (V) to Sb (III), and Sb···Cl weak intermolecular interactions have been observed. ESI-MS studies suggested that clusters 1-4 maintained their structural integrity in the solution state also. Solution NMR studies (1H, 31P, and 13C) support well the observed solid-state structures. 1-4 were tested for antibacterial activity using a microdilution assay. 1 and 4 showed the best activity with lower MIC values (0.78-6.25 μg/mL) against all the tested pathogens. The total antioxidant activity of 1-4 was evaluated through the phosphomolybdenum assay, which showed a total antioxidant activity ranging from 28.96 to 86.46 mg AAE/g compound with the ascorbic acid standard.

Scalable Manufacturing of Environmentally Stable All-Solid-State Plant Protein-Based Supercapacitors with Optimal Balance of Capacitive Performance and Mechanically Robust.

The development of advanced biomaterial with mechanically robust and high energy density is critical for flexible electronics, such as batteries and supercapacitors. Plant proteins are ideal candidates for making flexible electronics due to their renewable and eco-friendly natures. However, due to the weak intermolecular interactions and abundant hydrophilic groups of protein chains, the mechanical properties of protein-based materials, especially in bulk materials, are largely constrained, which hinders their performance in practical applications. Here, a green and scalable method is shown for the fabrication of advanced film biomaterials with high mechanical strength (36.3MPa), toughness (21.25MJm-3 ), and extraordinary fatigue-resistance (213000 times) by incorporating tailor-made core-double-shell structured nanoparticles. Subsequently, the film biomaterials combine to construct an ordered, dense bulk material by stacking-up and hot-pressing techniques. Surprisingly, the solid-state supercapacitor based on compacted bulk material shows an ultrahigh energy density of 25.8Whkg-1 , which is much higher than those previously reported advanced materials. Notably, the bulk material also demonstrates long-term cycling stability, which can be maintained under ambient condition or immersed in H2 SO4 electrolyte for more than 120 days. Thus, this research improves the competitiveness of protein-based materials for real-world applications such as flexible electronics and solid-state supercapacitors.

Computational design of the novel building blocks for the metal-organic frameworks based on the organic ligand protected Cu4 cluster

Abstract Metal-organic frameworks (MOFs) are tunable porous network compounds composed of inorganic nodes bound by various organic linkers. Here we report the density functional theory (DFT) study of the MOF novel building blocks made of the Cu4 clusters protected by four organic ligands having two phenyl rings and terminated either with Cl or Br atom (precursors 1 and 2, respectively). The research was performed both in the gas phase and with the implicit effects of acetonitrile included, with two functionals, B3LYP and PBE, both with and without the second-order dispersion correction. We analyzed the structural features of the precursors 1 and 2, their electronic structures, molecular electrostatic potential (MEP) distribution, and global reactivity parameters (GRPs). Both functionals resulted in the singlets of the precursors 1 and 2 as the most stable species. The precursor structures optimized with the hybrid functional were found to be quite similar for both halogens, both containing somewhat distorted from planarity Cu4 cluster, with the outer phenyls of the ligands rotated relative to the inner phenyls. With both halogens and both DFT approaches, the frontier molecular orbitals (FMOs) of the precursors 1 and 2 were shown to have quite similar compositions. The change of the substituent from Br to Cl was found to cause slight stabilizations or destabilizations of the HOMOs and LUMOs. The central parts and especially the inner phenyl ring parts of the precursors 1 and 2 were suggested to play a role of nucleophile in various chemical reactions due to the significant accumulation of negative electrostatic potential. Also, weak intermolecular interactions might exist between the ligands of neighboring precursor molecules. Finally, with both substituents the precursors 1 and 2 should be relatively unreactive and demonstrate thermodynamic stability. Further, the precursors 1 and 2 should be quite stable in oxidation reactions and more active in reduction processes. Generally, the substituent nature was shown not to affect significantly the reactivity of the precursors 1 and 2, as well as their other properties.

Electron density of a cyclic tetrasaccharide composed of benzoylated galactose units

Abstract The electron density distribution (EDD) of a cyclic tetrasaccharide composed of four benzoylated galactopyranosyl units was calculated from refinement with scattering factors from the invariom library based on X-ray diffraction data downloaded from the Crystal Structural Data Base (CSD). Bond topological and atomic properties have been derived. Benzoyl substituents cause weak intermolecular interactions. These are also visible from low electron density concentrations on the Hirshfeld surface and have an influence on a low X-ray density compared to that of non-substituted carbohydrates, where hydrogen bonds allow a 20% more dense packing. On the electrostatic potential (ESP) surface, a strong polarization between the positive outer belt of 12 benzoyl groups and a negative core region composed of the four galactose sugar molecules exists. The positive benzoyl exterior establishes a repulsive wall between adjacent molecules in the structure.

Selective chemisorption of polysulfides by porous molecular crystal: Cathode host materials for lean-electrolyte lithium-sulfur cells with high electrochemical stability

The development of high-energy-density lithium-sulfur batteries with porous substrate materials often meets the compromise between the facile accommodation of polysulfides and the fast electrolyte absorption. Porous molecular crystals (PMCs), a new class of organic porous materials assembled by discrete small molecules via weak intermolecular interactions, recently show their potential in energy storage. Cyclobenzoin ester (CE), as one of PMCs, features a high abundance of carbonyl groups as a porous molecule. In this study, we utilize the unique adsorption characteristics of CE as an effective sulfur host to design lean-electrolyte lithium-sulfur cells with excellent electrochemical stability. The porosity and polar carbonyl groups of CE provide an excellent chemisorption platform for polysulfides, while also enabling smooth electrolyte penetration. As a result, our sulfur-cyclobenzoin ester (sulfur-CE) energy storage material attains rigorous cell-design parameters with a low electrolyte-to-sulfur ratio (4 μL mg−1) and a high sulfur loading/content (4 mg cm−2 and 80 wt%), yet exhibits excellent electrochemical characteristics, including an outstanding discharge capacity of 907 mA h g−1, cyclability of 200 cycles, and a high rate performance from C/20 to 1C. This research opens a new strategy of selective chemisorption for simultaneously optimizing lean-electrolyte lithium-sulfur cells with both high active-material loadings and high cell stability.

Synthesis, Crystal Structure, Vibrational Study, Optical Properties and Hirshfeld Surface Analysis of a New Centrosymmetric Hybrid Material, Bis(3-Aminoquinolium) Tetrachloridocobaltate (II)

Abstract: The title organic-inorganic hybrid compound (C9H9N2)2[CoCl4] crystallizes at room temperature in the monoclinic C2/c space group. Its atomic arrangement can be described as an alternation of organic-inorganic layers along the c-axis. Crystal cohesion of the compound is achieved through N-H…Cl hydrogen bonds between the anions and cations and through cycle stacking interactions between organic cations. The vibrational properties were studied by Fourier Transform Infrared (FTIR) spectroscopy. The three-dimensional Hirshfeld surface (3D-HS) analysis and the two-dimensional fingerprint plots (2D-FP) were generated to quantify the weak intermolecular interactions present in the crystal. The optical properties were investigated by optical absorption and photoluminescence measurements. The band gap energy indicates that the compound behaves as an insulator material. Photoluminescence results suggest that the title compound can have a potential application as a non-linear optical material.

Generalizable Synthesis of Highly Fluorinated Ionic Liquids.

The unique chemistry of fluorocarbons (in particular, their weak intermolecular interactions and high degree of intrinsic free volume) makes them promising building blocks for ionic liquids with high gas capacities. Here, we report a generalizable method for the synthesis of fluorinated ionic liquids, which relies on the evolution of gaseous byproducts to drive product formation. This synthetic strategy overcomes solubility challenges that can hinder the synthesis of highly fluorinated ionic liquids via conventional methods and enables a systematic investigation of the effect of fluorination on ionic liquid viscosity and gas solubility.

Weak Solvent–Solvent Interaction Enables High Stability of Battery Electrolyte

Electrolytes play an important role in transporting metal ions (e.g., Li+) in metal ion batteries, while understanding the relationship between the electrolyte properties and behaviors is still challenging. Herein, we detect the existence of weak solvent–solvent interactions in electrolytes by nuclear magnetic resonance (NMR), particularly discovering that such interactions have a significant function of stabilizing the electrolytes, which has never been reported before. As a paradigm, we renovated the understanding of the role of ethylene carbonate (EC) solvent in the lithium-ion battery electrolyte. We find that the EC solvent can stabilize the linear carbonate solvent electrolyte, particularly the diethyl carbonate (DEC) electrolyte, by the weak intermolecular interactions, enhancing the energy difference between the orbitals of the Li+(EC)x(DEC)y complex, in turn demonstrating strong capability against reduction. Our viewpoint was further demonstrated in other metal ion batteries (e.g., Na+, K+), whose discovery is significant for designing electrolytes and in-depth understanding of the battery performance.

Deciphering the ground state of a C3-symmetrical Blatter-type triradical by CW and pulse EPR spectroscopy

3,3′,3′'-(Benzene-1,3,5-triyl)tris(1-phenyl-1H-benzo[e][1,2,4]triazin-4-yl) (1) is a C3-symmetrical triradical comprised of three Blatter radical units connected at the 1, 3, 5 positions of a central trimethylenebenzene core. This triradical has an excellent air, moisture, and thermal stability. Single-crystal XRD indicates that triradical 1 adopts a propeller-like geometry with the benzotriazinyl moieties twisted by 174.1(2)° and packs in 1D chains along the c axis to form an extensive network of weak intermolecular interactions. Frozen solution continuous wave (CW) EPR spectra and variable-temperature field-sweep echo-detected (FSED) spectra revealed an intramolecular ferromagnetic exchange within the spin system, supporting a quartet S = 3/2 ground state. DFT calculations further supported these experimental findings.

Chirality as a Feature of the Crystal Structure of Lanthanide Ion Complexes—Some Simple Examples

Single-crystal X-ray structure determinations are reported for four lanthanide complexes, [Dy(bipy)2Cl2(OH2)2]Cl.H2O (bipy = 2,2′-bipyridine), 1; [La2(phen)2(O2CCH3)4(NO3)2] (phen = 1,10-phenanthroline), 2; [Lu(terpy)(O2CCH3)3].NaNO3 (terpy = 2,2′;6′,2″-terpyridine) 3; and [Lu(phen)(O2CH)3(OH2)].H2O, 4. Dispersion interactions within the stacked arrays of coordinated aza-aromatic units found in all four complexes appear to be a significant structural influence in the solid state. For complex 1, there are additional interactions beyond dispersion, which suggests that it may be the means whereby the Δ and Λ forms contribute to the overall chiral nature of the crystal. These weak intermolecular interactions were investigated in detail using the Hirshfeld surface analysis.