Asymmetric Molecules Research Articles

High-Performance Small Molecule Organic Solar Cells Enabled by a Symmetric-Asymmetric Alloy Acceptor with a Broad Composition Tolerance.

Using a combinatory blending strategy is demonstrated as a promising path for designing efficient organic solar cells (OSCs) by boosting the short-circuit current density and fill factor. Herein, a high-performance ternary all-small molecule OSC (all-SMOSCs) using a narrow-bandgap alloy acceptor containing symmetric and asymmetric molecules (BTP-eC9 and SSe-NIC) and a wide-bandgap small molecule donor MPhS-C2 is reported. Introducing the synthesized SSe-NIC into the MPhS-C2:BTP-eC9 host system can broaden the absorption spectrum, modulate energy offsets, and optimize the molecular packing of the host materials. After systematically optimizing the weight ratio of MPhS-C2:BTP-eC9:SSe-NIC, a champion efficiency of 18.02% is achieved. Impressively, the ternary system not only delivered a broad composition tolerance with device efficiencies over 17% throughout the whole blend ratios, but also exhibited less non-geminate recombination and energy loss, and better-light-soaking stability than the corresponding binary systems. This work promotes the development of high-performance ternary all-SMOSCs and heralds their brighter application prospects.

Environment polarity effects on the microscopic nonlinear optical properties of some asymmetrical azobenzene molecules

Solvent as a complex environment can surround solute molecules and modify their function. In this work, different solute–solvent interaction effects on the nonlinear optical behavior of some azo dyes were studied at the molecular level. In this case, spectroscopic technique and density functional theory were used. According to the results, molecular dipole transition, changes between ground and excited state dipole moments, substituent, and environment polarity play considerable effects on the molecular nonlinear optical responses. In addition to solvent effects on the molecular first- and second-order hyperpolarizability, the two-photon absorption cross-section is also modified due to solvent-induced interactions. Moreover, the determination of the contribution of dominant solvent effects on the molecular nonlinear optical behavior can facilitate the studies on the application of optical samples in designing various optical systems.

Sensitivity of explosive materials to the action of electromagnetic fields

The analysis was done to define the most common methods of detection and disposal of explosive objects. According to the principle of their operation, the methods were subdivided into 4 classes. It was established that physical methods are the most effective, and most of them are based on the use of electromagnetic waves with various parameters. To define the degree of ef-fect of electromagnetic waves on explosive materials it was reasonable to study their electromag-netic properties. It is shown that the main parameter that quantitatively characterizes the degree of sensitivity of explosive materials to the action of electromagnetic fields is the dipole moment of their molecules. The molecular structure of the most common explosive materials, in particular hexogen, pentaerythritol tetranitrate and trinitrotoluene, tetryl, lead trinitroresorcinate, mercu-ryfulminate and lead azide has been analyzed. It is shown that the molecules of these substances have a two-dimensional structure, while the molecules of hexogen, pentaerythritol tetranitrate, and mercury fulminate are symmetrical. It corresponds to the absence of a dipole moment in such molecules. The dipole moments of asymmetric molecules of trinitrotoluene, tetryl, lead trinitrore-sorcinate, and lead azide were calculated using the method of adding force vectors of dipole moments of interatomic bonds. The calculated data showed that the dipole moments of these sub-stances are significant, so the electromagnetic influence on the activation of these explosive mate-rials cannot be neglected. Partially, the high values of the dipole moments of trinitrotoluene (µ(C7H5N3O6)=2,55 D) and tetryl (µ(C7H5N5O8)=9,27 D) can be explained by an increased num-ber of asymmetric bonds with nitrogen that has a high electronegativity. The obtained data can be used for the development of the safety algorithms to provide a safe work of the rescuers during demining of the territory and when using the devices of an active electromagnetic action in order to prevent the uncontrolled detonation of explosive objects

Tandem organic solar cells with 20.6% efficiency enabled by reduced voltage losses.

Large voltage losses are the main obstacle for achieving high efficiency in organic solar cells (OSCs). Here we construct ternary OSCs by introducing an asymmetric small molecule acceptor AITC into PBDB-TCl : BTP-eC9 system and demonstrate the effectiveness in simultaneously decreasing energy disorder and non-radiative voltage losses. It is found that the introduction of AITC can modify domain size and increase the degree of crystallinity, which enhances open-circuit voltage and power conversion efficiency (19.1%, certified as 18.9%). Inspiringly, an output efficiency of 20.6% of the constructed tandem OSCs based on PBDB-TCl : AITC : BTP-eC9 ternary active layer output a recorded efficiency of 20.6% (certified as 20.3%), which is the highest value in OSCs field to date. This work demonstrates that decreasing the voltage losses by ternary strategy and constructing of tandem architecture are effective approaches towards improving photovoltaic performance.

N-Annulated Perylene Diimide Non-Fullerene Acceptors for Organic Photovoltaics

This work covers the development of non-fullerene acceptors for use in organic photovoltaics built using the N-annulated perylene diimide dye. The classic perylene diimide dye has been extensively used to construct non-fullerene acceptors, leading to device power conversion efficiencies of over 10%. Strong visible light absorption and deep frontier molecular energy levels have made such materials (both molecular and polymeric) near ideal for pairing with narrow-gap conjugated polymers in bulk-heterojunction active layers. The N-annulation of the dye provides an extra site for side-chain engineering and alters the electronic structure of the polycyclic aromatic core. In addition, N-annulation allows for selective bromination of the perylene core, leading to building blocks that are useful for the construction of large molecular frameworks using the atom-economical direct heteroarylation cross-coupling method. Herein, we detail a series of molecules developed by our team that are based on the N-annulated perylene diimide in the form of dimers with different cores (both electron-rich and electron-deficient); dimers with varied side chains; tetramers with varying geometries; and large, asymmetric molecules with internal energy cascades. The use of these molecules as non-fullerene acceptors in organic photovoltaic devices (binary and ternary blends, outdoor and indoor light applications, and spin-coated vs. slot-die-coated photoactive layers) is presented.

Efficient ternary organic solar cells enabled by asymmetric nonfullerene electron acceptor with suppressed nonradiative recombination

The open-circuit voltage (Voc) of organic solar cells (OSCs) is still far from the Shockley-Queisser limit due to the large non-radiative voltage loss (ΔVocnonrad). Reducing energy loss (Eloss) to obtain higher Voc without sacrificing Jsc and FF is the key to achieve further improvement in power conversion efficiency (PCE) of OSCs. In this work, we designed and synthesized a new asymmetric nonfullerene acceptor via a dual asymmetric strategy, named as SN-O. Under the synergistic effect of alkoxy chain and nitrogen atom substitution, the LUMO and HOMO energy levels of SN-O are significantly elevated compared to Y6, allowing SN-O to display a high open-circuit voltage with a reduced nonradiative energy loss (ΔEnonrad = 0.177 eV). The alkoxy side chain of SN-O brings an intramolecular conformational locking effect and the large dipole moment of asymmetric molecules facilitate the aggregation properties in thin films. The good miscibility allows Y6 and SN-O to form alloy acceptor attributing to the similar chemical structures. The addition of SN-O as the third component into the D18:Y6 system showed a significant reduction in the nonradiative energy loss and a favorable blend film morphology, thus improves exciton dissociation, charge transport and collection. Consequently, a high PCE of 18.3% was achieved for D18:Y6:SN-O ternary system with simultaneously enhancement of Voc, Jsc and FF, which is much higher than that of the binary devices.

Selective Expression of Organic P hosphorescence Units: When H-Benzo[f]indole Meets 7H-Benzo[c]carbazole

Phosphorescence selective expression in the development of ultralong organic room-temperature phosphorescence (UORTP) materials to enrich the properties and functions of smart materials is a very interesting topic but has not been realized yet due to the lack of organic phosphorescence units. In this work, we, for the first time, investigate the selective expression phenomenon of two organic phosphorescence units in a single molecule. First, we report a new phosphorescence unit 7H-benzo[c]carbazole (BCz) with the advantage of simple synthesis. BCz derivatives (PNBCz-1 and PNBCz-2) feature photoactivated green ultralong phosphorescence in the PMMA film at room temperature, and cation radicals are involved in the unique ultralong phosphorescence behavior, which is similar to H-benzo[f]indole (Bd) derivatives. Different from Bd, pure powders of BCz derivatives show intense red-shifted ultralong phosphorescence at 77 K, probably due to the extended π conjugated structure of BCz. Then, BCz and Bd were incorporated into a single skeleton and two asymmetric molecules (PNBCzBd-1 and PNBCzBd-2) were obtained. Surprisingly, in the PMMA film, PNBCzBd-1 and PNBCzBd-2 both show photoactivated yellow ultralong phosphorescence at room temperature assigned to the intrinsic phosphorescence emission of Bd, and intrinsic green phosphorescence of BCz is almost screened by Bd. Density functional theory (DFT) calculations reveal that the incorporation of Bd leads to the shifting of the phosphorescence emission centers from BCz units to Bd units. Therefore, the intrinsic phosphorescence emission of Bd is selectively expressed in the case of PNBCzBd-1 and PNBCzBd-2. To our best knowledge, this is the first example that reports the selective expression behavior of organic phosphorescence units. We believe that this study may impact the future research of UORTP materials and lay the foundation for their future applications.

Chiral Binaphthol Fluorescent Materials Based on a Novel Click Reaction

Because of easy functionalization, low cost, and large-scale fabrication, pure organic fluorescent polymers are widely applied in light-emitting display, bio-fluorescence-enhanced imaging, explosive detection, and other fields. Among these applications, due to their unique optical rotation characteristics, chiral fluorescent polymer materials are part of fluorescent polymers which could be used in chiral molecular detection and separation, biological target detection, etc. In this work, we designed and synthesized the first chiral organic fluorescent polysulfate materials through sulfur fluoride exchange polymerization (new click chemistry) by asymmetric binaphthol molecular. The chiral fluorescent polysulfate were synthesized by R/S [1,1′-binaphthalene]-2,2′-diol(Binol.), propane-2,2-diylbis(4,1-phenylene) bis(sulfurofluoridate) (FO2S–BA–SO2F) and 4,4′-(propane-2,2-diyl)diphenol(BA.) through step-by-step polymerization reaction under alkali present. It was found that the local crystallization of pure bisphenol A polysulfate was broken by the asymmetric axial chiral BINOL molecule inserted in it and let the polymer into the amorphous state. Fluorescent chiral molecules are uniformly dispersed in the polymer; the 120 µm film prepared by the film scraper was transparent and had good luminescence characteristics under ultraviolet light. After fluorescence detection, the excitation wavelength is 450 nm, and the emission wavelength is 480 and 517 nm.

Designing of asymmetric non-fullerene based acceptor materials by re-modification of π-spacers with PCE > 20 % for organic solar cell

In this study, four new organic molecules with different compounds called the π-linkers, embedded between dithieno[3,2-b:2′,3′-d]pyrrole donor core and dicyanoindanone end-capped acceptor molecules were theoretically designed and analyzed to be proposed as the new asymmetric small molecule acceptors (SMAs) with the highest power conversion efficiency (PCE) in non-fullerene organic solar cells (OSCs). The charge transportability, stability, electronic, and optical properties were calculated based on the molecular structure analysis with the density functional theory (DFT) approach and the results were compared with dithieno[3,2-b:2′,3′-d]pyrrole based asymmetric SMAs named TPIC with dicyanoindanone end-capped groups. As a result of efficient π-π stacking, the energy differences decreased by 17.71 % and the charge transport increased by 49 %. The molecules showed broad absorption spectra ranging from 400 nm to 1200 nm with significant redshifted wavelength towards the near IR region coupled with low excitation energies. The LUMO energy level of the external donor PM7 is aligned with HOMO energy levels of the architecture acceptor molecules via bandgap tuning and the open-circuit voltage (VOC) increased from 1.002 V to 2.44 V for the highest combination PM7:C4. The efficacious charge transport properties, high excitonic generation with low excitation energies, facile separation, and increased VOC via band-gap tunning; all four designed molecules achieved a champion PCE ranging from 20 % to 34 % at short circuit current density 9, 12, and 15 mA cm−2. The molecules exhibited the highest PCE value for any asymmetric non-fullerene small molecule acceptor-based organic solar cells.

Backward scattering impact on the photoionization time delay of asymmetric molecules

The time delays in photoionization of asymmetric diatomic molecules are numerically investigated using the technique of reconstruction of attosecond beating by interference of two-photon transitions (RABBITTs). Our results show that two different oscillatory structures appear in the molecular photoionization time delays as the photoelectron energy changes, and the contribution of these two oscillations to the time delays varies with the nuclear distance. By using an analytical interference model, we demonstrate that one oscillation is traced back to the two-center interference and the other originates from the photoelectrons backward scattering. With the increases of internuclear distance, the backward scattering impact on the time delays is gradually distinct in a particular direction of the photoionization. The amplitude of the backward scattering induced oscillation decreases when the photoelectron energy increases. Furthermore, the stereo RABBITT time delays display a distinct downshift as the increases of asymmetry degree of molecule, which is attributed to the increasing depth of the additional Coulomb potential experienced by the ionized electron.

Design of Diverse Asymmetric Pockets in De Novo Homo-oligomeric Proteins.

A challenge for design of protein-small-molecule recognition is that incorporation of cavities with size, shape, and composition suitable for specific recognition can considerably destabilize protein monomers. This challenge can be overcome through binding pockets formed at homo-oligomeric interfaces between folded monomers. Interfaces surrounding the central homo-oligomer symmetry axes necessarily have the same symmetry and so may not be well suited to binding asymmetric molecules. To enable general recognition of arbitrary asymmetric substrates and small molecules, we developed an approach to designing asymmetric interfaces at off-axis sites on homo-oligomers, analogous to those found in native homo-oligomeric proteins such as glutamine synthetase. We symmetrically dock curved helical repeat proteins such that they form pockets at the asymmetric interface of the oligomer with sizes ranging from several angstroms, appropriate for binding a single ion, to up to more than 20 Å across. Of the 133 proteins tested, 84 had soluble expression in E. coli, 47 had correct oligomeric states in solution, 35 had small-angle X-ray scattering (SAXS) data largely consistent with design models, and 8 had negative-stain electron microscopy (nsEM) 2D class averages showing the structures coming together as designed. Both an X-ray crystal structure and a cryogenic electron microscopy (cryoEM) structure are close to the computational design models. The nature of these proteins as homo-oligomers allows them to be readily built into higher-order structures such as nanocages, and the asymmetric pockets of these structures open rich possibilities for small-molecule binder design free from the constraints associated with monomer destabilization.

High resolution spectroscopy of asymmetric top molecules in nonsinglet electronic states: the ν3 fundamental of chlorine dioxide (16O35Cl16O) free radical in the X2B1 electronic ground state.

Highly resolved spectra of the 16O35Cl16O isotopologue of chlorine dioxide were recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer in the region of the ν3 band. The analysis was made in the frame of the spin-rotational effective Hamiltonian (in A-reduction and Ir-representation) taking into account spin-rotational coupling operators up to the sixth order and the corresponding reduction of the Hamiltonian. The mathematical description of the ro-vibrational spectra was implemented to the specially created computer program ROVDES. Under the present experimental conditions, we were able to assign more than 5200 spin-rotational transitions to the ν3 band. This number is 2.4 times higher compared to the previous studies available from the literature. The vibrational ground state parameters were improved, and the 2220 upper spin-rotation-vibration energy levels were determined and used as initial data in the inverse spectroscopic problem with the derived effective spin-rotational Hamiltonian. A total of 37 fitted parameters were determined (22 rotational and centrifugal parameters and 15 parameters of spin-rotation coupling). The appearance of strong Coriolis resonance interactions between the (001) and (100) vibrational states in the sets of (001)[N,Ka = 9], (001)[N,Ka = 17], (001)[N,Ka = 18] and (001)[N,Ka = 19] spin-rotation-vibration levels was experimentally observed for the first time and explained. The drms = 1.4 × 10-4 cm-1 reproduction of the initial "experimental" upper ro-vibrational energy values was achieved which is considerably better compared to the use of parameters from a previous study ([J. Ortigoso et al., J. Mol. Spectrosc., 1992, 155, 25-43]).

Tautomerization of single asymmetric oxahemiporphycene molecules on Cu(111).

We have studied 22-oxahemiporphycene molecules by a combination of scanning tunneling microscopy at low temperatures and density functional theory calculations. In contrast to other molecular switches with typically two switching states, these molecules can in principle exist in three different tautomers, due to their asymmetry and three inequivalent binding positions of a hydrogen atom in their macrocycle. Different tautomers are identified from the typical appearance on the surface and tunneling electrons can be used to tautomerize single molecules in a controllable way with the highest rates if the STM tip is placed close to the hydrogen binding positions in the cavity. Characteristic switching processes are explained by the different energy pathways upon adsorption on the surface. Upon applying higher bias voltages, deprotonation occurs instead of tautomerization, which becomes evident in the molecular appearance.

Probing the Structure of Asymmetric Planar Molecules Using Odd-Even High Harmonics

Probing the Structure of Asymmetric Planar Molecules Using Odd-Even High Harmonics

Asymmetric Wigner molecules in nanowire Y-junctions

The possibility of crystalline states of interacting electrons, known as Wigner crystals, has been intensively studied in each of the three dimensions. One-dimensional (1D) systems, however, can be interconnected forming two-dimensional (2D) lattices, being a three-terminal Y-junction (Y-J) the simplest one. Then, even when electrons in the individual branches of the Y are confined in 1D, as the Y-J is in 2D, one could expect significant differences in the crystalline state of the electron gas in a Y-J. With the recent report of fabrication of defect-free GaAs/AlGaAs Y-Js by epitaxial methods, the study of semiconductor Y-Js acquires a special relevance due to its eventual direct exploration. Here, by considering the collective electron interactions using a Yukawa-like effective potential, we explore a two-electron distribution in nanowire Y-Js by modulating its electron density via a screening parameter. We find that the electrons changes from a quasi-continuous to a Wigner molecule-like distribution when the electron density decreases in the Y-J. In bold contrast to the strict 1D case, where equidistant distributions of equal density are obtained in the Wigner regime, in the Y-J equidistant distributions of asymmetric density are induced. We also explore the effect of an external electric field acting along the Y-axis on the asymmetric distributions.

Asymmetric cobalt porphyrins for oxygen reduction reactions: Boosted catalytic activity by the use of triphenylamine

Asymmetric metalloporphyrins have been rarely investigated in oxygen reduction reaction (ORR), which is probably due to the remaining unclear structural effects on electrocatalytic performance and the low synthetic yields. A remarkable feature of these molecules is their inherent large dipole moments, which can benefit the charge separation and electron density modification. Here we synthesize two asymmetric molecules A-Cb-CoPor and A-TPA-CoPor by substituting one of the meso-positions with carbazole and triphenylamine (TPA) derivatives, respectively, to coat on carbon black as ORR electrocatalysts. Density functional theory calculations suggest the well separation of electron density on the cobalt porphyrins. The electrochemical performances of the composites are performed in acid with comparing to a symmetric Co porphyrin-coated catalyst CoPor1/C. A-TPA-CoPor/C attains better ORR activity and selectivity than A-Cb-CoPor/C due to the structural merits of TPA unit. However, an identical electron transfer number of 3.6 is obtained by A-TPA-CoPor/C and CoPor1/C, which is possibly a trade-off result of the use of TPA from its structural advantage and deleterious electron-donating ability. Impressively, both asymmetric porphyrin-based composites exhibit greater limiting current densities than CoPor1/C, which mainly originates from the reduced charge transfer resistance as suggested by the impedance measurements. Our work demonstrates the promise of the asymmetric molecular approach as a viable strategy for efficient ORR catalysts.

Intramolecular Assembly of Nitrobiazoles and an Ether Bridge: Toward Energetic Materials with Enhanced Energy and Safety.

Recently, the construction of novel fused-ring frameworks has become one of the most significant innovative approaches to access high-energy and thermostable energetic molecules. In this work, an ether bridge was utilized as a building block to construct energetic fused-ring skeletons for the first time. Two new [5,7,5]-tricyclic N-heterocycle-based backbones, ditriazole-1,3,6-oxadiazepine and pyrazole-triazole-1,3,6-oxadiazepine, were synthesized via a straightforward one-step synthetic route and the energetic performances of their derivatives were further evaluated. Containing an additional oxygen atom, high-density pyrazole-triazole backbone, and high crystal packing coefficient, the asymmetric molecule 2,10,11-trinitro-5H,7H-pyrazolo[1,5-c][1,2,4]triazolo[5,1-e][1,3,6]oxadiazepine (NOB-3) features a high crystal density of 1.825 g cm-3, much superior to those of the symmetrical analogues 2,10-dinitro-5H,7H-bis([1,2,4]triazolo)[1,5-c:5',1'-e][1,3,6]oxadiazepine (NOB-4, d = 1.758 g cm-3) and D (d = 1.634 g cm-3). Meanwhile, the compounds NOB-3 and NOB-4 exhibit better thermal stability than the parent molecule DNBT (Td = 251 °C), and their decomposition temperatures reach up to 303 and 294 °C, respectively. The remarkable overall performance of NOB-3 and NOB-4 strongly suggests them as appropriate candidates for heat-resistant explosives. Our study may give new insights into the close correlation of the structural properties of energetic fused-ring frameworks, and the universality of the asymmetric heterocycles combination strategy for designing advanced high-energy density materials (HEDMs) was emphasized again.

Two asymmetric small molecule acceptors with aromatic and non-aromatic ring side chains were developed for organic solar cells

Asymmetric side-chain engineering has been demonstrated to be an effective approach for modifying the solubility and morphology of non-fullerene small molecule acceptors (NF-SMAs). However, prior research has mostly concentrated on optimizing the length and branching locations of alkyl chains. Phenyl and cyclohexyl groups suspended on the side chains have been shown to be effective for tuning the crystallinity and self-assembly of symmetric organic molecules for efficient organic solar cells. To investigate the impact of the aromatic and non-aromatic ring side chains on the performance of asymmetric NF-SMAs, two asymmetric acceptors, Y-Ph4F and Y–CH4F, are designed with phenyl and cyclohexyl as two distinct side chains, respectively, in this work. Due to their common backbone, the two NF-SMAs exhibit similar absorption spectra and energy levels as determined by UV–vis absorption, cyclic voltammetry, and density functional theory calculations. Differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD) demonstrate that Y–CH4F with 4-cyclohexylbutyl side chains has stronger molecular packing and crystallinity in the solid state compared to Y-Ph4F with 4-phenylbutyl side chains. By pairing these NFAs with a well-known polymer donor PM6, both PM6:Y-Ph4F and PM6:Y-Ph4F-based organic solar cells (OSCs) achieve power conversion efficiencies (PCEs) of more than 15%. When fabricated with a 1 cm2 active area, the Y-Ph4F and Y–CH4F-based devices can also obtain exceptional PCEs of 15.05% and 14.10%, respectively. These findings suggest that the aromatic and non-aromatic ring side chains can effectively tune the molecular packing and crystallinity for efficient OSCs.

Regulation of Continuum Harmonic Generation by Using Near-infrared Chirped Pulses

It has been known that the broadband of continuum harmonics, a regular periodicity or a wide smooth range, is essential for generating attosecond pulses. However, the high-order rescatterings of electrons (HOR) can significantly affect this important part of high-order harmonic spectra. In the present work, we apply the method suggested in our previous studies to limit the HOR effect on the continuum harmonics by using up-chirped pulses with frequency increasing in time to regulate the high-order harmonic generation of an asymmetric molecule such as CO subjected to a near-infrared laser. To do so, we numerically calculate the high-order harmonic spectra using the time-dependent wave functions obtained within the framework of the single-active electron approximation. To analyze and regulate the HOR effect, we use the time-frequency analysis together with the kinetic energy maps obtained from the equation of electron motion in the laser electric field. These techniques reveal the high-order harmonic dynamics, especially the effect of chirped pulse on the manifestation of continuum harmonics. Based on this, we release the notice on choosing appropriate parameters to obtain the optimal continuum range of harmonics. Although the detailed analysis is given for the CO molecule, the method suggested is applicable for other polar molecules.

Crystal structure of bis-{3-(3-bromo-4-methoxyphenyl)-5-[6-(1H-pyrazol-1-yl)pyridin-2-yl]-1,2,4-triazol-3-ato}-iron(II) methano-l disolvate.

The unit cell of the title compound, [FeII(C17H12BrN6O)2]·2MeOH, consists of a charge-neutral complex mol-ecule and two independent mol-ecules of methanol. In the complex mol-ecule, the two tridentate ligand mol-ecules 2-[5-(3-bromo-4-meth-oxy-phen-yl)-4H-1,2,4-triazol-3-yl]-6-(1H-pyrazol-1-yl)pyridine coordinate to the FeII ion through the N atoms of the pyrazole, pyridine and triazole groups, forming a pseudo-octa-hedral coordination sphere around the central ion. In the crystal, neighbouring asymmetric mol-ecules are linked through weak C-H(pz)⋯π(ph) inter-actions into chains, which are then linked into layers by weak C-H⋯N/C inter-actions. Finally, the layers stack into a three-dimensional network linked by weak inter-layer C-H⋯π inter-actions between the meth-oxy groups and the phenyl rings. The inter-molecular contacts were qu-anti-fied using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative contributions of the contacts to the crystal packing to be H⋯H 34.2%, H⋯C/C⋯H 25.2%, H⋯Br/Br⋯H 13.2%, H⋯N/N⋯H 12.2% and H⋯O/O⋯H 4.0%. The average Fe-N bond distance is 1.949 Å, indicating the low-spin state of the FeII ion. Energy framework analysis at the HF/3-21 G theory level was performed to qu-antify the inter-action energies in the crystal structure.