Ligand Field Research Articles

Magnetism of single-doped paramagnetic tin clusters studied using temperature-dependent Stern-Gerlach experiments with enhanced sensitivity: impact of the diamagnetic ligand field and paramagnetic dopant.

In this work, the magnetic properties of tetrel clusters SnNTM, which are singly doped with transition metals (TM), are investigated. On the one hand, the number of tetrel atoms (N = 11, 12, 14 and 17 with TM = Mn) is varied; on the other hand, different transition metals (N = 14, TM = Cr, Mn, Fe) are studied. Magnetic deflection experiments under cryogenic conditions show that the variation of the number of tetrel atoms strongly changes the magnetic properties of the Mn-doped clusters. It is observed that Sn12Mn, Sn11Mn and Sn14Mn partially show super-atomic behaviour, while spin relaxation occurs in Sn17Mn. Magnetic deflection experiments at higher nozzle temperatures were carried out for the first time enhanced by a second parallel-aligned Stern-Gerlach magnet to achieve larger deflections. The resulting temperature-dependent one-sided deflections are quantitatively analysed using Curie's law and show that Sn17Mn possesses the highest magnetic moment of these clusters, followed by Sn12Mn and Sn11Mn. Sn14Mn shows the lowest magnetic moment. The replacement of Mn by Cr in Sn14Mn leads to a diamagnetic singlet, i.e., the magnetic moment of Cr in Sn14Cr is completely quenched. The replacement of Mn by Fe in turn leads to a paramagnetic species, whereby Sn14Fe is most likely present as a triplet. On this basis, the geometrical and electronic structures are analysed using quantum chemical calculations, indicating an arachno-type structure for Sn14Cr, Sn14Mn and Sn14Fe, which has already been predicted in the literature for Si14Cr. This is experimentally confirmed by deflection of molecular beams with an electric field under cryogenic conditions, suggesting that the arachno-type geometry is crucial for the overall stability of the transition-metal-doped tetrel clusters Sn14TM with TM = Cr, Mn, Fe.

Synergism of Light-Induced [4 + 4] Cycloaddition and Electron Transfer Toward Switchable Photoluminescence and Single-Molecule Magnet Behavior in a Dy4 Cubane.

Molecular materials possessing switchable magneto-optical properties are of great interest due to their potential applications in spintronics and molecular devices. However, switching their photoluminescence (PL) and single-molecule magnet (SMM) behavior via light-induced structural changes still constitutes a formidable challenge. Here, a series of cubane structures were synthesized via self-assembly of 9-anthracene carboxylic acid (HAC) and rare-earth ions. All complexes exhibited obvious photochromic phenomena and complete PL quenching upon Xe lamp irradiation, which were realized via the synergistic effect of photogenerated radicals and [4 + 4] photocycloaddition of the AC components. The quenched PL showed the largest fluorescence intensity change (99.72%) in electron-transfer photochromic materials. A reversible decoloration process was realized via mechanical grinding, which is unexpectedly in the electron-transfer photochromic materials. Importantly, an SMM behavior of the Dy analog was observed after room-temperature irradiation due to the photocycloaddition of AC ligands and the photogenerated stable radicals changed the electrostatic ligand field and magnetic coupling. Moreover, based on the remarkably photochromic and photoluminescent properties of these compounds, 2 demos were applied to support their application in information anti-counterfeiting and inkless printing. This work, for the first time utilizing the simultaneous modulation of photocycloaddition and photogenerated radicals in one system, realizes complete PL quenching and light-induced SMM behavior, providing a dynamical switch for the construction of multifunctional polymorphic materials with optical response and optical storage devices.

Revisiting the role of octahedral symmetry in the interpretation of spectroscopic properties of [OsF6]2- and PtF6 complexes.

The electronic structure of [OsF6]2- and PtF6 complexes was studied by means of CASSCF/NEVPT2 multiconfigurational calculations, including spin-orbital coupling, which is very relevant in the case of these metals. From these calculations, it is possible to establish that in the octahedral symmetry (Oh), the ground state is non-magnetic (Jeff = 0) because of the strong ligand field, and the interaction with paramagnetic excited states is almost negligible, resulting in a non-magnetic behavior, which is in agreement with the experimental evidence.

Highly efficient circularly polarized electroluminescence based on chiral manganese(ii) complexes.

Currently reported circularly polarized luminescent devices are primarily based on rare earth and noble metal complexes or lead perovskite materials. Reports on electroluminescent devices employing eco-friendly luminescent materials are notably scarce. In this study, we strategically designed and synthesized manganese complexes featuring Binapo as the chiral ligand. The complex structure reveals a tetrahedral coordination configuration, with the R/S configurations exhibiting a mirror relationship. Leveraging the strong ligand field and chiral structural characteristics of Binapo, the enantiomers display red emission and exhibit significant circularly polarized luminescence with a circularly polarized luminescence asymmetric factor (g lum) of 5.1 × 10-3. The circularly polarized electroluminescent performance was investigated by using a solution processing method and host-guest doping strategy. Our efforts resulted in device performance with an external quantum efficiency (EQE) exceeding 4%, and its electroluminescent asymmetric factor (g EL) reached an impressive -8.5 × 10-3. This surpasses the performance of most devices relying on platinum (Pt) and iridium (Ir) metal complexes and perovskite related materials. Our work establishes a pathway for the development of cost-effective and environmentally friendly chiral electroluminescent materials and devices.

Enhancing the high-spin reactivity in C-H bond activation by Iron (IV)-Oxo species: insights from paclitaxel hydroxylation by CYP2C8.

Previous theoretical studies have revealed that high-spin states possess flatter potential energy surfaces than low-spin states in reactions involving iron(IV)-oxo species of cytochrome P450 enzymes (P450s), nonheme enzymes, or biomimetic complexes. Therefore, actively utilizing high-spin states to enhance challenging chemical transformations, such as C-H bond activation, represents an intriguing research avenue. However, the inherent instability of high-spin states relative to low-spin states in pre-reaction complexes often hinders their accessibility around the transition state, especially in heme systems with strong ligand fields. Counterintuitively, our investigation of the metabolic hydroxylation of paclitaxel by human CYP2C8 using a hybrid quantum mechanics and molecular mechanics (QM/MM) approach showed that the high-spin sextet state exhibits unusually high stability, when the reaction follows a secondary reaction pathway leading to 6β-hydroxypaclitaxel. We thoroughly analyzed the factors contributing to the enhanced stabilization of the high-spin state, and the knowledge obtained could be instrumental in designing competent biomimetic catalysts and biocatalysts for C-H bond activation.

Supramolecular crystals of Mn(15-crown-5)(MnCl4)(DMF) with dielectric phase transition, high quantum yield and phase transition-induced luminescence enhancement behavior.

The supramolecular crystals, Mn(15-crown-5)(MnCl4)(DMF), (1; 15-crown-5 = 1,4,7,10,13-pentaoxacyclopentadecane), were synthesized via a self-assembly strategy under ambient conditions. Comprehensive characterization of the crystals involved microanalysis for C, H, and N elements, thermogravimetric (TG) analysis, differential scanning calorimetry (DSC) and single-crystal X-ray diffraction techniques. The results reveal that 1 undergoes a two-step thermotropic and isostructural phase transition at around 217 K and 351 K upon heating. All three phases belong to the same space group (P212121) with analogous cell parameters. These two phase transitions primarily involve the thermally activated ring rotational dynamics of the 15-crown-5 molecule, with only the transition at ca. 351 K being associated with a dielectric anomaly. 1 exhibits intense luminescence with a peak at ∼600 nm and a high quantum yield of 68%. The mechanisms underlying this intense luminescence are likely linked to low-symmetry ligand fields. Additionally, 1 displays phase transition-induced luminescence enhancement behavior, and the possible mechanism is further discussed.

Dynamic metal-linker bonds in metal-organic frameworks.

Metal-linker bonds serve as the "glue" that binds metal ions to multitopic organic ligands in the porous materials known as metal-organic frameworks (MOFs). Despite ample evidence of bond lability in molecular and polymeric coordination compounds, the metal-linker bonds of MOFs were long assumed to be rigid and static. Given the importance of ligand fields in determining the behaviour of metal species, labile bonding in MOFs would help explain outstanding questions about MOF behaviour, while providing a design tool for controlling dynamic and stimuli-responsive optoelectronic, magnetic, catalytic, and mechanical phenomena. Here, we present emerging evidence that MOF metal-linker bonds exist in dynamic equilibria between weakly and tightly bond conformations, and that these equilibria respond to guest-host chemistry, drive phase change behavior, and exhibit size-dependence in MOF nanoparticles.

Influence of graphene on the electronic and magnetic properties of an iron(III) porphyrin chloride complex.

Although iron-based single atom catalysts are regarded as a promising alternative to precious metal catalysts, their precise electronic structures during catalysis still pose challenges for computational descriptions. A particularly urgent issue to be addressed is the influence of the environment on the electronic structure, and how to describe this accurately using computational methods. Here, we study an iron porphyrin chloride complex adsorbed on a graphene sheet using density functional theory calculations to probe how much the electronic structure is influenced by the presence of a graphene layer. Our results indicate that weak interactions due to van der Waals forces dominate between the porphyrin complex and graphene, and only a small amount of charge is transferred between the two entities. Furthermore, the interplay of the ligand field environment, strong p-d hybridization, and correlation effects within the complex are strongly involved in determining the spin state of the iron ion. By bridging molecular chemistry and solid state physics, this study provides first steps towards a joint analysis of the properties of iron-based catalysts from first principles.

Construction of intermolecular σ-hole interactions in rare earth metallocene complexes using a 2,3,4,5-tetraiodopyrrolyl anion.

The generation of noncovalent intermolecular interactions represents a powerful method to control molecular vibrations and rotations. Combining these with the axial ligand field enforced by the metallocene ligand scaffold provides a dual-pronged approach in controlling the magnetic-relaxation pathways for dysprosium-based single-molecule magnets (SMMs). Here, we present the first implementation of 2,3,4,5-tetraiodopyrrole (TIPH) in its anionic form [TIP]- as a ligand in three isostructural rare-earth metal complexes Cp*2RE(TIP) (1-RE, RE = Y, Gd, and Dy; Cp* = pentamethylcylopentadienyl), where the TIP ligand binds through the nitrogen and one iodine atom κ2(N,I) to the metal centre. The shallow potential energy surface of the intermolecular σ-hole interaction yields distortions of the interatomic distances at elevated temperatures which were investigated by variable-temperature SCXRD. 1-RE constitute the first crystallographically characterized molecules containing TIP as a ligand for any metal ion, and 1-Dy is the first SMM that employs the TIP ligand. The structural dependence on temperature allowed the mechanism of magnetic relaxation to be explored through ab initio calculations at different temperatures. The electronic influence of the coordinated iodine substituent was probed via magnetometry and cw-EPR spectroscopy on 1-Gd. To further scrutinize the impact of the iodine substituents on the physical properties, a second set of new complexes Cp*2RE(DMP) (2-RE, RE = Y, and Dy) where DMP = 2,5-dimethylpyrrolyl were synthesized. Here, the DMP ligand binds similarly to the TIP ligand and represents an all-hydrocarbon analogue to 1-RE. 2-Dy constitutes the first SMM bearing a DMP ligand.

Constructing high axiality mononuclear dysprosium molecular magnets via a regulation-of-co-ligands strategy.

Two lanthanide complexes with formulae [DyIII(LN5)(pentafluoro-PhO)3] (1) and [DyIII(LN5)(2,6-difluoro-PhO)2](BPh4) (2) (LN5 = 2,14-dimethyl-3,6,10,13,19-pentaazabicyclo[13.3.1]nonadecal (19),2,13,15,17-pentaene) were structurally and magnetically characterized. DyIII ions lie in the cavity of a five coordinate nitrogen macrocycle, and in combination with the introduction of multi-fluorinated monodentate phenoxyl coligands a high axiality coordination symmetry is built. Using the pentafluorophenol co-ligand, complex 1 with a D2d coordination environment, is obtained and displays moderate single-molecule magnets (SMMs) behavior. When difluorophenol co-ligands were used, a higher local axisymmetric pentagonal bipyramidal coordination geometry was observed in complex 2, which displays apparent slow magnetic relaxation behavior with a hysteresis temperature of up to 5 K. Further magnetic studies of diluted samples combined with ab initio calculations indicate that the high axiality plays a crucial role in suppressing quantum tunneling of magnetization (QTM) and consequently results in good slow magnetic relaxation behavior. Different fluoro-substituted phenoxyl co-ligands have phenoloxy oxygen atoms with different electrostatic potentials as well as a different number of phenoloxy coligands along the magnetic axis, resulting in different ligand field strengths and coordination symmetries.

A highly anisotropic family of hexagonal bipyramidal Dy(III) unsaturated 18-crown-6 complexes exceeding the blockade barrier over 2700 K: a computational exploration.

In the present work, we have explored a series of unsaturated hexa-18-crown-6 (U18C6) ligands towards designing highly anisotropic Dy(III) based single-ion magnets (SIMs) with the general formula [Dy(U18C6)X2]+ (where U18C6 = [C12H12O6] (1), [C12H12S6] (2), [C12H12Se6] (3), [C12H12O4S2] (4), [C12H12O4Se2] (5) and X = F, Cl, Br, I, OtBu and OSiPh3). By analysing the electronic structure, bonding and magnetic properties, we find that the U18C6 ligands prefer stabilising the highly symmetric eight-coordinated hexagonal bipyramidal geometry (HBPY-8), which is the source of the near-Ising type anisotropy in all the [Dy(U18C6)X2]+ complexes. Moreover, the ability of sulfur/selenium substituted U18C6 ligands to stabilize the highly anisotropic HBPY-8 geometry makes them more promising towards engineering the equatorial ligand field compared to substituted saturated 18C6 ligands where the exodentate arrangement of the S lone pairs results in low symmetry. Magnetic relaxation analysis predicts a record barrier height over 2700 K for [Dy(C12H12O6)F2]+ and [Dy(C12H12S6)X2]+ (where X = F, OtBu and OSiPh3) complexes, nearly 23% higher than those of the top performing Dy(III) based SIMs in the literature.

Iron(II) spin crossover complexes of tetradentate Schiff-bases: tuning T1/2 by choice of formyl-heterocycle component.

Four new tetradentate Schiff-base ligands were prepared in situ from the 1 : 2 condensation of 1,3-diaminopropane and either 2-thiazolecarboxaldehyde (L2thiazole), 4-thiazolecarboxaldehyde (L4thiazole), 4-oxazolecarboxaldehyde (L4oxazole), or 5-bromopyridine-2-aldehyde (L5Br-pyridine), and complexed with [Fe(NCS)2(pyridine)4] to give four monometallic FeII complexes, [Fe(Lheterocycle)(NCS)2]. Structural characterisation shows the expected octahedral FeII centres in all cases, with Lheterocycle occupying the equatorial plane and the two thiocyanate ligands trans to each other, resulting in an N6 coordination sphere. Solid state magnetic measurements showed that the two complexes with the thiazole-based ligands exhibit the beginning of a spin transition above 300 K, with T1/2 = 350 K for [Fe(L4thiazole)(NCS)2] and 400 K for [Fe(L2thiazole)(NCS)2], whereas the 4-oxazole-based ligand gives [Fe(L4oxazole)(NCS)2] which remains high spin at all measured temperatures (50-400 K). Interestingly, [Fe(L5Br-pyridine)(NCS)2] crystallised as two solvent-free polymorphs: magnetic measurements on samples with both polymorphs present showed a two step SCO with an abrupt transition at T1/2 = 245 K assigned to the transition in polymorph A (as this was also seen in a sample of pure polymorph A), and a gradual transition at T1/2 = 304 K assigned to polymorph B. These findings show that the order of increasing ligand field strength for these heterocycles is 4-oxazole ≪ 5Br-pyridine < 4-thiazole < 2-thiazole.

Bridge editing of spin-flip emitters gives insight into excited state energies and dynamics.

Six-coordinate chromium(iii) complexes with high spin-flip (SF) photoluminescence quantum yields and lifetimes (molecular rubies) have attracted huge interest in the past years due to their applicability in sensing, photocatalysis or circularly polarised emission. However, clearcut design rules for high quantum yields and lifetimes are still lacking due to the multidimensional problem of the non-radiative decay of the SF states. Based on an isostructural series of complexes differing in the ligand backbone, we disentangle decisive structural and electronic features for SF excited state energies and non-radiative decays promoted by spin-orbit coupling, Jahn-Teller distortions and (thermally activated) multiphonon relaxation. This analysis goes beyond the classical increasing of the ligand field strength or the metal-ligand covalency to reduce non-radiative decay or to tune the SF energy. The results underscore the utility of the combination of near-infrared absorption, variable temperature emission and fs-transient absorption spectroscopy as well as photolysis and high-level quantum chemical calculations to obtain a comprehensive picture of the excited dynamics on ultrafast and long timescales.

Binuclear methylphosphinidine complexes of cyclopentadienylruthenium carbonyls: effects of the higher ligand field strength of ruthenium derivatives relative to iron derivatives.

The structures and energetics of the binuclear methylphosphinidene complexes of cyclopentadienylruthenium carbonyls of the type [MePRu2(CO)nCp2] (n = 4, 3, 2, 1) have been investigated for comparison with their previously studied iron analogues. For the tetracarbonyls and tricarbonyls [MePM2(CO)nCp2] (n = 4, 3) substituting ruthenium for iron has relatively little effect on the energetically preferred structures. Thus such structures have two-electron donor bridging MeP groups with no metal-metal bond for the tetracarbonyls and a metal-metal single bond for the tricarbonyls. This leads to favored 18-electron configurations for both ruthenium atoms in all cases. However, the higher ligand field strengths of ruthenium complexes relative to analogous iron complexes have major effects on the energetically preferred structures for the dicarbonyls and monocarbonyls [MePM2(CO)nCp2] (M = Fe, Ru; n = 2, 1). Thus the 11 lowest energy structures for the dicarbonyl [MePFe2(CO)2Cp2] are triplet or quintet spin state structures whereas the 6 lowest energy structures for the ruthenium analogue [MePRu2(CO)2Cp2] are all singlet structures. These low-energy singlet [MePRu2(CO)2Cp2] structures include species in which both ruthenium atoms attain the favored 18-electron configurations in different ways: either by a Ru-Ru single bond and an agostic C-H-Ru interaction from the methyl group, a Ru-Ru single bond and a four-electron donor bridging MeP ligand with PRu double bonds, or a formal RuRu double bond with a two-electron donor bridging MeP ligand. The 8 lowest energy structures for the diiron monocarbonyl [MePFe2(CO)Cp2] are all triplet or quintet spin structures whereas the lowest energy structure for the diruthenium monocarbonyl [MePRu2(CO)Cp2] by more than 20 kcal mol-1 is a singlet structure with a formal RuRu double bond and bridging CO and four-electron donor MeP groups. Thermochemical information predicts such monocarbonyl derivatives to be the dominant binuclear decarbonylation products of the tricarbonyls [RPRu2(CO)3Cp2] by thermal or photochemical methods.

Exploring spin states and ligand field splitting in metal complexes: a theoretical analysis of spin-orbital interactions and magnetic properties.

Metal complexes are pivotal in diverse fields due to their wide array of functionalities, including magnetism, conductivity, and photoresponsiveness. These functionalities are intricately linked to the phenomenon of ligand field splitting, yet controlling the magnitude of this splitting within metal complexes presents a significant challenge. This study aims to address this challenge by developing a novel 2D spectrochemical series, integrating two critical parameters: metal ions and ligands. Employing the DV-Xα molecular orbital method, we directly calculated ligand field splitting width, enabling a detailed assessment of energy splitting trends. Our results reveal that the magnitude of ligand field splitting, encompassing 17 metal types and 29 ligand types, can be precisely controlled. This represents a significant advancement over traditional spectrochemical series, such as those proposed by R. Tsuchida, which predominantly focus on either ligands or metals in isolation. Additionally, our study extends to the calculation of spin states in these metal complexes, contributing valuable insights for the development of magnetic materials. We demonstrate that the relative ligand field splitting and spin polarization can be used to predict spin states, offering a new perspective in material design and functionality. These findings not only enhance our understanding of ligand field splitting in metal complexes but also provide a comprehensive framework for predicting their electronic and magnetic properties, paving the way for innovative applications in material science and coordination chemistry.

Towards superior structural, optical and magnetic properties, and ligand field effects of $${\text{B}}_{2} {\text{O}}_{3}$$–ZnO–CoO glass doped with alkaline metal earth cations

Towards superior structural, optical and magnetic properties, and ligand field effects of $${\text{B}}_{2} {\text{O}}_{3}$$–ZnO–CoO glass doped with alkaline metal earth cations

The Holohedrization Effect in Ligand Field Models

The ligand field theory is an early and yet perennial class of quantum models accounting for the optical and magnetic properties of metal ions as a function of their environment in compounds. In the context of modern quantum chemistry, in order to predict properties from first principles, the ligand field paradigm can serve to illuminate the black box of heavy calculations, extracting heuristic meaning and causal roots. The genuine ligand field models are tacitly affected by an artificial feature, so-called holohedrization. It induces an inversion symmetry, even in cases where the local geometry does not show this element. This aspect received little attention over decades of using the ligand field Hamiltonians. In this work, we systematically investigate, assisted by state-of-the-art ab initio computer experiments, whether holohedrization is a hidden drawback of early models or if it also appears in realistic modeling. We found that the holohedrization trend also appears when using data from modern ab initio calculations.

Prediction of 4f-5d Transition Energy of Ce3+ in Oxides By First-Principles Calculations and Machine Learning

A Ce3+ ion has only one electron in the 4f orbitals and its 4f-5d transition energy is strongly influenced by the width of the crystal field splitting of the 5d orbitals. In other words, the absorption and emission wavelengths of Ce3+ in crystals can be widely controlled by changing the ligand field environment. As an example of Ce3+-doped phosphor, Ce:YAG (Y3Al5O12) is widely used as an yellow phosphor for standard white LEDs. Therefore, novel phosphors with desired emission colors can be developed by adding Ce3+ to appropriate host crystals.In this work, we aimed to construct an efficient prediction model for the transition energy of Ce3+ in oxide crystals. Small clusters consisting of the substituted Ce3+ ion and the first-neighbor anions were constructed and molecular orbital calculations were performed using the relativistic discrete-variational Xα (DV-Xα) method. Then machine learning based on structural and electronic state parameters was performed to create a predictive model for the 4f-5d transition energy of Ce3+ in crystals. By creating the correlation diagrams, the influence of each parameter on the transition energy was analyzed in detail.

Unlocking same-sign CPL: solvent effects on spectral form and racemisation kinetics in nine-coordinate chiral europium(III) complexes.

Understanding the factors that shape the circularly polarised luminescence (CPL) emission profiles of europium(III)-based CPL emitters to have specific sign properties, e. g. monosignate individual CPL transitions, is key to design novel complexes for applications ranging from advanced security inks to bio-probes for live cell imaging. In order to correlate structure and spectral characteristics, a photophysical and kinetic investigation has been conducted on a series of coordinatively saturated nine-coordinate europium(III) systems based on 1,4,7-triazacyclononane. We highlight that lanthanide emission is sensitive to changes in the ligand field by showing the linear dependence of total emission intensity ratios as a function of solvent polarity, for europium(III) complexes displaying an internal charge transfer (ICT) excited state. This sensitivity increases by a factor of 20 when studying changes in CPL spectra, rendering these complexes accurate probes of local polarity. Solvent polarity, solvent-specific effects, and the nature of the chromophores' coordinating donor atoms strongly influence the kinetic stability of europium(III) complexes with respect to enantiomer interconversion. Notably, we show that the choice of donor groups to coordinating to europium(III) and the nature and polarity of the solvent affects the rate of racemisation, leading to systems with very long half-lives at room temperature in non-polar media.

Enhancing Spin-Transport Characteristics, Spin-Filtering Efficiency, and Negative Differential Resistance in Exchange-Coupled Dinuclear Co(II) Complexes for Molecular Spintronics Applications.

Single-molecule spintronics, where electron transport occurs via a paramagnetic molecule, has gained wide attention due to its potential applications in the area of memory devices to switches. While numerous organic and some inorganic complexes have been employed over the years, there are only a few attempts to employ exchange coupled dinuclear complexes at the interface, and the advantage of fabricating such a molecular spintronics device in the observation of switchable Kondo resonance was demonstrated recently in the dinuclear [Co2(L)(hfac)4] (1) complex (Wagner et al., Nat. Nanotechnol. 2013, 8, 575-579). In this work, employing an array of theoretical tools such as density functional theory (DFT), the ab initio CASSCF/NEVPT2 method, and DFT combined with nonequilibrium Green Function (NEGF) formalism, we studied in detail the role of magnetic coupling, ligand field, and magnetic anisotropy in the transport characteristics of complex 1. Particularly, our calculations not only reproduce the current-voltage (I-V) characteristics observed in experiments but also unequivocally establish that these arise from an exchange-coupled singlet state that arises due to antiferromagnetic coupling between two high-spin Co(II) centers. Further, the estimated spin Hamiltonian parameters such as J, g values, and D and E/D values are only marginally altered for the molecule at the interface. Further, the exchange-coupled state was found to have very similar transport responses, despite possessing significantly different geometries. Our transport calculations unveil a new feature of the negative differential resistance (NDR) effect on 1 at the bias voltage of 0.9 V, which agrees with the experimental I-V characteristics reported. The spin-filtering efficiency (SFE) computed for the spin-coupled states was found to be only marginal (∼25%); however, if the ligand field is fine-tuned to obtain a low-spin Co(II) center, a substantial SFE of 44% was noted. This spin-coupled state also yields a very strong NDR with a peak-to-valley ratio (PVR) of ∼56 - a record number that has not been witnessed so far in this class of compounds. Additionally, we have established further magnetostructural-transport correlations, providing valuable insights into how microscopic spin Hamiltonian parameters can be associated with SFE. Several design clues to improve the spin-transport characteristics, SFE and NDR in this class of molecule, are offered.