Lone Pair Research Articles

Quantifying Structural Polarization by Continuous Regulation of Lone-Pair Electron Expression in Molecular Crystals.

Rational design of structural polarization is vital for modern technologies, as it allows the physical properties of functional materials to be tailored. An effective approach for governing polarization involves the utilization of stereochemical lone-pair electrons (LPEs). However, despite the recognized significance of LPEs in controlling structural polarization, there remains a lack of understanding regarding the quantitative relationship between their expression and the extent of structural polarization. Here, by using pressure to continuously tune the LPE expression, we achieve the precise control and quantification of structural polarization, which brings enhanced second harmonic generation (SHG) of the molecular crystal SbI3·3S8. We introduce the I-Sb-I angle (α̅) that describes the degree of LPE expression and establishes a quantitative relationship between α̅ and structural polarization. That is, decreasing α̅ shapes LPE expression from delocalization to localization, which repels the bonding pairs of electrons and thus enhances the structural polarization. In addition, we extend this quantified relationship to a series of molecular crystals and demonstrate its applicability to the design of structural polarization by tailoring LPE expression.

Preparation of a high-performance synthetic pitch from aromatic hydrocarbons containing N/Cl

The preparation of a synthetic pitch from aromatic monomers could easily regulate structure orientation at the molecular level, which would be useful in fabrication. An isotropic synthetic pitch was prepared by a chlorine- and/or nitrogen-induced substitution polymerization reaction method using aromatic hydrocarbon precursors containing Cl and N, which for this study were chloromethyl naphthalene and quinoline. This method was verified by investigating the structural changes under different synthesis conditions, and the synthesis mechanism induced by aromatics containing Cl was also probed. The result shows that the pyridinic N in quinoline contains a lone pair of electrons, and is an effective active site to induce the polymerization reaction by coupling with aromatic hydrocarbons containing Cl. The reaction between such free radicals causes strong homopolymerization and oligomerization. A higher reaction temperature and longer reaction time significantly increased the degree of polymerization and thus increased the softening point of the pitch. A linear molecular structure was formed by the Cl substitution reaction, which produced a highly spinnable pitch with a softening point of 258.6 °C, and carbon fibers with a tensile strength of 1 163.82 MPa were obtained. This study provides a relatively simple and safe method for the preparation of high-quality spinnable pitch.

Selective Hydroboration of C-C Single Bonds without Transition-Metal Catalysis.

Selective hydroboration of C-C single bonds presents a fundamental challenge in the chemical industry. Previously, only catalytic systems utilizing precious metals Ir and Rh, in conjunction with N- and P- ligands, could achieve this, ensuring bond cleavage and selectivity. In sharp contrast, we discovered an unprecedented and general transition-metal-free system for the hydroboration of C-C single bonds. This methodology is transition-metal and ligand-free and surpasses the transition-metal systems regarding chemo- and regioselectivities, substrate versatility, or yields. In addition, our system tolerates various functional groups such as Ar-X (X=halides), heterocyclic rings, ketones, esters, amides, nitro, nitriles, and C=C double bonds, which are typically susceptible to hydroboration in the presence of transition metals. As a result, a diverse range of γ-boronated amines with varied structures and functions has been readily obtained. Experimental mechanistic studies, density functional theory (DFT), and intrinsic bond orbital (IBO) calculations unveiled a hydroborane-promoted C-C bond cleavage and hydride-shift reaction pathway. The carbonyl group of the amide suppresses dehydrogenation between the free N-H and hydroborane. The lone pair on the nitrogen of the amide facilitates the cleavage of C-C bonds in cyclopropanes.

Computational scrutiny of psychoactive cannabinoids through molecular electrostatic potential and CB1 receptor interaction

Delta-9-THC and psychoactive derivatives were scrutinized with molecular electrostatic potential (MEP) and ligand-CB1 interaction. At the B3LYP/6-31G** level, MEP maps of the most active cannabinoids (mac), pKi ≥ 6.72 (1-13), revealed that the directional orientation of the lone pair of electrons in the phenolic OH, in general, produces a greater interaction with the substituent at position C9, orienting the carbocyclic ring system, reflecting the psychoactivity of the compounds. In addition, the existence of the side alkyl chain contributes to improving this property. In less active cannabinoids (lac), pKi < 6.72 (14-22), the negative MEP shows a more spread out, “diluted” electron density, probably due to the orientation of the carbocyclic ring system unfavorable to the pharmacophoric conformation. Furthermore, the MEP maps show cannabinoids 14-22 presenting small differences in the distribution of this density, when compared to 1-13, which seems crucial to the decrease in psychoactivity. When examining the ligand-CB1 interaction, the orientations of the compounds were shown to be governed basically by the hydrophobic pockets between helices III, IV, VI, and VII; with the most active alkyl fragment (1-13) directed to the hydrophobic site, the nonpolar fragment (methylcyclohexene) to the hydrophobic pocket, the phenolic OH to the hydrophilic pocket and the oxane fragment oriented to a small hydrophilic pocket of CB1. In the lac (14-22), the poses of the substituents COOH (14), COOCH3 (16), and COCH3 (22) were oriented towards a hydrophobic pocket and 15, 17, 18, and 21 presented the oxygenated groups directed to the hydrophilic sites of the CB1 receptor. The OH substituent in 19 directs it to the hydrophobic pocket and 20, with the OH group but distant from phenolic OH, presents said group also directed to this hydrophobic pocket of CB1. The scrutiny of cannabinoids with MEP and the ligand-CB1 interaction could guide the design of new molecules with better psychoactivity.

Differing Effects of Nonlinearity around the Proton Acceptor on CH··O and NH··O H-Bond Strength within Proteins.

The effects of deviations from nonlinearity around the carbonyl proton acceptor of an amide group are assessed by DFT quantum chemical calculations for both CH··O and NH··O H-bonds. The proton donors are the imidazole functional group of His and the indole of Trp, which are paired respectively with N-methylacetamide and acetamide. The displacement of either CH or NH group toward the carbonyl O sp2 lone pairs stabilizes the system and strengthens the H-bond. But the two donor groups differ in their response to a shift out of the amide plane. While the NH··O H-bond is weakened by this displacement, a substantial strengthening is observed when the CH donor is moved out of this plane, in one direction versus the other. This pattern is explained on the basis of simple Coulombic considerations.

From nonemission to nearly unity quantum yield: Breaking parity-forbidden transitions in rubidium indium chloride through 5s2 lone pair Sb-doping

Halide perovskites doped with ns2 metal ions have stimulated widespread research owing to their efficient and stable self-trapped emissions. Here we observe the strictly forbidden transition 3P0→1S0 is broken and afford nearly unity triplet orange self-trapped excitons (O-STEs) emission, through 5 s2 lone pair Sb cation doping in host Rb2InCl5·H2O single crystal. In particular, additional triplet blue self-trapped excitons (B-STEs) emission centered at 475 nm, stemming from partially allowed 3P1→1S0, is also observed. Spectroscopic characterization along with literature analysis demonstrates that the behavior of forbidden transition breaking originates from the mixing of 3P0 and 3P1 states. First-principles density-functional theory (DFT) calculations as well confirm the involvement of atomic orbitals in bandgap construction, as evidence of 5s5p-5 s2 transition, affording the STEs emission. Combining the efficient, stable broad emission Rb2In96.39 %Cl5·H2O: 3.61 % Sb3+ crystal with Cs3Cu2Cl5 and Cs3Cu2I5 phosphors, a lead-free white light-emitting diode with a high color rendering index of 93.4 has been achieved. Furthermore, the unique sensitive and steep temperature dependence photoluminescence (PL) lifetimes may prompt this type of self-trapped zero-dimensional (0D) perovskites to great potential in the field of thermometry application.

Optimization of Functional Building Blocks Generates a Substantial Improvement in Birefringence from Sn2OSO4 to Sn3O2(OH)(HSO4).

In this work, two tin(II)-based sulfates, Sn2OSO4 and Sn3O2(OH)(HSO4), were synthesized via the mild hydrothermal method. Both compounds employ the Sn2+ cation with stereochemically active lone pair (SCALP) electrons and non-π-conjugated tetrahedral anionic groups SO4 as the functional structural blocks. Interestingly, the experimental birefringence of Sn3O2(OH)(HSO4) is 0.169@546 nm, approximately 42 times larger than that of Sn2OSO4, which is 0.004@546 nm. Detailed structural analysis and theoretical calculations suggest that this significant birefringence difference arises from the optimization of functional building blocks in coordination environments and spatial arrangements. Furthermore, both compounds exhibit ultraviolet absorption edges at 308 and 307 nm, respectively. This indicates that Sn3O2(OH)(HSO4) has the potential to be a candidate for an ultraviolet (UV) birefringent crystal. This study offers inspiration for further exploration of tin(II)-based compounds with excellent comprehensive properties.

Is the Presence of Sn2+ a Crucial Factor for the Generation of Low Thermal Conductivity in Tin-Based Sulfides?

Comprehending the relationship between crystal structures and transport properties is crucial to develop materials with improved electrical and thermal properties for thermoelectric applications. In this article, we report on the complex crystal structure and physical properties of Cr2Sn3S7, a n-type magnetic semiconductor with a low energy band gap and low thermal conductivity. Importantly, we demonstrate that the high level of structural complexity is related to the coexistence of two sublattices: a host lattice, [Cr4Sn2S11]2-, characterized by a mixed Sn4+/Cr3+ occupancy of its cationic sites, and a guest lattice characterized by [Sn4S3]2+ chains, containing Sn2+ cations only, closely related to the ones encountered in the orthorhombic SnS compound. By combining experiments including X-ray diffraction with ab initio calculations of electrons and phonons, we succeeded to elucidate the origin of the low thermal conductivity in Cr2Sn3S7. We demonstrate that the low dimensionality of the [Sn4S3]2+ chains, which generates weak Sn···S interactions with the 3D host lattice, is induced by the lone pair stereochemical activity of Sn2+. This lattice softening favors strong anisotropic vibrations at low frequencies, highlighting the primordial role played by Sn2+ cations in both crystal structure dimensionality and low thermal conductivity in tin-based sulfides.

Charge reconstruction from simultaneous Fe coordination and P/O co-doping in g-C3N4 for efficient photo-reductive recovery of uranium(VI)

The risk of radionuclide leakage always threats ecological security and human health, making the recovery of uranium from nuclear wastewater a meaningful and urgent issue. However, the low-cost and efficient capture of uranium remains a challenge at present. In this study, a homemade photocatalyst of iron coordinated graphitic carbon nitride (g-C3N4) co-doped with phosphorus and oxygen (OPFCN), which was facilely synthesized through a novel one-step thermal polymerization method, exhibited superior photoelectric efficiency and photocatalytic activity towards the photo-reductive capture of uranium(VI). The simultaneous Fe coordination and P/O co-doping in framework of g-C3N4 played a synergistic effect in charge reconstruction, in which electrons migration driven by coordinated Fe and lone electron pairs delocalization from doped P/O enormously increased electron density and enhanced charge transfer, thus effectively promoting the separation of photogenerated charge carriers. The specific surface area, pore volume and average pore size of OPFCN reached 70.2 m2·g−1, 0.157 cm3·g−1 and 7.78 nm, respectively, exhibiting a trend increasingly beneficial for photocatalytic adsorption and mass transfer with successive introduction of Fe, P and O into original g-C3N4. With the simultaneous introduction of Fe, P and O, the optical absorption edge underwent a significant redshift and fluorescence emission intensity dropped by 75 % compared to that of CN, demonstrating the enhanced visible light capturing ability and significantly inhibited recombination of photogenerated charge carriers in OPFCN. As a result, a uranium capture rate of over 98 % was achieved with catalyst dosage of only 5:1 at pH 5 with OPFCN, demonstrating its competitive photo-reductive activity towards uranium(VI) uptake compared with previously reported g-C3N4-based photocatalysts. Meanwhile, OPFCN exhibited remarkable reusability and stability with even over 65 % uranium recovery rate and almost unchanged peak patterns in XRD and FT-IR in fifth reuse recycle. Additionally, it was demonstrated that e− and O2•− were the direct active species to realize the photoreduction of uranium(VI) over OPFCN, in which e− played the dominant role. The modification method of simultaneous Fe coordination and P/O co-doping would be expected to effectively promote the utilization of g-C3N4-based photocatalysts towards photo-reductive recovery of uranium(VI) from radioactive wastewater.

Phenytoin from antiepileptic to covid-19: Synthesis, crystal structure, DFT, HSA, MEP and green biological study of phenytoin derivative as potential covid-19 drug candidates

That's an interesting point! Phenytoin's potential in reducing cognitive deficits during COVID-19 is indeed intriguing. Its established status as an approved antiepileptic medication could lend credibility to exploring its effects on cognitive function in COVID-19 patients. This dual functionality could provide a unique angle for research and potential therapeutic interventions. This study reports the synthesis, characterization and importance of a new phenytoin derivative PD, C23H24N4O5. A biological molecular modelling study using a computer-aided tool, which is a clean technique of PD compared to the approved Phenytoin anti-COVID-19 drugs, was achieved. Docking the three compounds into 7JQ0 of COVID-19 Mpro showed the potential capability of PD compared to Phenytoin and the inhibitor. Binding affinity, for example, was -7.3, -6.9 and -6.6 kcal/mol, respectively. Noticeably, PD interacted with 75 % of the essential functional Mpro amino acids, such as G143 and H164, M49, C145, M165 and E166, comparable to the standards used. Further interesting findings that predicted compound toxicity and drug-likeness also found that PD was less toxic and bio-available as a drug than Phenytoin and the inhibitor. Superposition of our ligand PD against Phenytoin and the Inhibitor docked into7JQ0 using the same parameters showed similar interactions in the amino acid cavity, enhancing the possibility of PD being an anti-COVID-19 drug. The free computer-aided methods were used to significantly speed up the initial stages of drug discovery by narrowing down potential candidates for further laboratory testing.This compound adopts an L-shaped conformation. The lone pairs on the ring nitrogen atoms participate in π bonding in the ring. In the crystal, a layer structure was generated by NH···N, NH···O and CH···O hydrogen bonds plus CH···π(ring) interactions. Theoretical studies of the compound were calculated using the density functional theory (DFT) method with a B3LYP 6–311++G(d,p) basis set. The geometrical parameters after optimization were compared with the experimental values. Molecular Electrostatic Potential (MEP) and Hirshfeld Surface Analysis (HSA) were studied to investigate intermolecular interactions. Frontier Molecular Orbitals (FMOs), which were Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO), were created, and the energy gap between these orbitals was calculated to understand the chemical stability of the molecule.

Strong Triel Bonds with Be as Electron Donor.

A systematic theoretical study was conducted on the triel bonds (TrBs) within the TrX3···Be(CO)3 complexes (Tr = B, Al, Ga, In, Tl; X = H, F, Cl, Br, I). The interaction energies of these systems range between 4 and 38 kcal/mol. The TrB weakens as X becomes more electronegative in the B and Al systems, while the opposite pattern of stronger bonds is observed in the In and Tl analogues. The dominant component of the TrB is polarization energy, which arises from charge transfer from Be(CO)3 to TrX3. The source of the density is a confluence of CO π-bonding orbitals at the Be center that resembles a Be lone pair, and which makes the molecular electrostatic potential above the Be somewhat negative. This π-lump is paired with the highly positive π-hole above the Tr, and a large amount of charge is transferred to the empty pz orbital of Tr. These factors, when considered in conjunction with large AIM measures, confer on this TrB a certain degree of covalency.

Pyridazine‐Promoted Construction of Vinylene‐Linked Covalent Organic Frameworks with Exceptional Capability of Stepwise Water Harvesting

AbstractIn this study, we successfully developed two novel vinylene‐linked covalent organic frameworks (COFs) using 2‐connected 3,6‐dimethylpyridazine through Knoevenagel condensation. These COFs featured finely tailored micro‐/nano‐scale pore sizes, high surface areas and stable non‐polar vinylene linkages. Finely resolved powder X‐ray diffraction patterns demonstrated highly crystalline structures with a hexagonal lattice in the AA layer stacking. The resulting one‐dimensional channels possess strong hydrogen‐bond accepting sites arising from the decorated cis‐azo/azine units with two pairs of fully exposed lone pair electrons, endowing the as‐prepared COFs with exceptional water absorption properties. The g‐DZPH‐COF exhibited successive steep water uptake steps starting from low relative pressures (P/PSTA=0.1), with the remarkable water uptake capacity of 0.26 g/g at P/PSTA=0.2 (25 °C), which is the optimal value recorded among the reported COFs. Dynamic vapour sorption measurements revealed the fast kinetics of these COFs, even in the cluster formation process. Water uptake and release cycling tests demonstrated their outstanding hydrolytic stability, durability, and adsorption–desorption retention ability.

Pyridazine-Promoted Construction of Vinylene-Linked Covalent Organic Frameworks with Exceptional Capability of Stepwise Water Harvesting.

In this study, we successfully developed two novel vinylene-linked covalent organic frameworks (COFs) using 2-connected 3,6-dimethylpyridazine through Knoevenagel condensation. These COFs featured finely tailored micro-/nano-scale pore sizes, high surface areas and stable non-polar vinylene linkages. Finely resolved powder X-ray diffraction patterns demonstrated highly crystalline structures with a hexagonal lattice in the AA layer stacking. The resulting one-dimensional channels possess strong hydrogen-bond accepting sites arising from the decorated cis-azo/azine units with two pairs of fully exposed lone pair electrons, endowing the as-prepared COFs with exceptional water absorption properties. The g-DZPH-COF exhibited successive steep water uptake steps starting from low relative pressures (P/PSTA=0.1), with the remarkable water uptake capacity of 0.26 g/g at P/PSTA=0.2 (25 °C), which is the optimal value recorded among the reported COFs. Dynamic vapour sorption measurements revealed the fast kinetics of these COFs, even in the cluster formation process. Water uptake and release cycling tests demonstrated their outstanding hydrolytic stability, durability, and adsorption-desorption retention ability.

Tetrel Bond Affects the Self-Assembly of Acetylcholine and its Analogues and is an Ancillary Interaction in Protein Binding.

The -N+(CH3)3 residue is present in acetylcholine (ACh) and in many of its analogues which are used as selective ACh agonist or antagonists for human therapy. The X-ray structures of four ACh derivatives show the presence of short and linear contacts between the C atoms of -N+(CH3)3 groups and lone pair possessing atoms. These contacts can be rationalized as tetrel bonds (TtBs) thanks to their geometric features. Interrogation of the Protein Data Bank suggests that similar -N+-C⋅⋅⋅nucleophile contacts affect the details of the binding of ACh and its derivatives to proteins. Quantum theory of atoms in molecules, noncovalent interaction plot, and natural bond orbital analyses consistently confirm that the -N+-C⋅⋅⋅nucleophile contacts observed in small molecule crystals and in substrate/protein complexes are attractive in nature and can be rationalized as TtBs. TtBs involving methyl groups of the -N+(CH3)3 moiety can be proposed as a new item in the palette of interactions allowing the compounds containing this pharmacophoric unit to bind to their target protein and/or to express their biological/pharmacological properties.

Density functional theory study on frustrated Lewis pairs catalyzed C‐H activation of heteroarenes: Mechanism variation tuning by electronic effect

AbstractUnreactive C‐H bond activation is a new horizon for frustrated Lewis pairs (FLPs) chemistry. Although concerted mechanism (Science 2015, 349, 513) and stepwise carbene mechanism (Org. Lett. 2018, 20, 1102) have been proposed for the FLPs catalyzed C‐H bond activation of 1‐methylpyrrole, the influence of electronic properties of FLPs on the reaction mechanism is far away from well‐understood. In this study, an assortment of P‐B type FLPs with different electronic characteristic was employed to study the catalyzed C‐H bond activation of 1‐methylpyrrole by using density functional theory calculations. Detailed calculations demonstrated that the reactivity variation and the reaction mechanism binary of FLPs catalyzed C‐H activation can be varied by tuning electronic effect of Lewis base center. On the one hand, the concerted C‐H activation reactivity is mainly controlled by the electron donation of the lone pair of Lewis base center; thus, the FLPs with electron‐donating substituents (FLP1, FLP2, and FLP3) catalyzed the C‐H bond activation through concerted mechanism. On the other hand, the reactivity of stepwise carbene mechanism is mostly attributed to the vacant orbital of Lewis acid center; as a result, the FLP5 bearing ‐P(C6F5)2 preferred to catalyzed the bond activation through concerted mechanism. In contrast, a metathesis mechanism through strained four‐membered ring transition state is less feasible. These results should provide deeper insight and broader perspective to understand the structure and function of FLPs for rational design of FLPs catalyzed C‐H bond activation.

Azatriangulenetrione as the Anode Material for Sodium-Ion Batteries: Reversible Redox Chemistry Mediated by Lone Pair Electrons.

Redox-active organic molecules have potential as electrode materials, but their cycling stability is often limited by the irreversible formation of σ-bonds from the radical intermediates. Herein, we present an effective approach to achieve high reversibility by using lone pair electrons to mediate intramolecular radical-radical coupling. Azatriangulenetrione (1) was examined as the anode in sodium-ion batteries, which displayed a reversible four-step, one-electron redox chemistry. In situ electron spin resonance, ex situ Fourier transform infrared/X-ray photoelectron spectroscopy, and density functional theory calculation revealed that the unstable radical anions can couple with each other through the lone pair electrons of the central nitrogen atom, leading to stabilized radical species. Furthermore, scan-rate-dependent cyclic voltammetry measurements and galvanostatic intermittent titration techniques demonstrated that the redox reaction kinetics for radical formation were much faster than the radical paring process. This study offers deep insights into the design of highly reversible organic electrodes.

Preparation and characterization of pyrimidine‐cored covalent organic frameworks for heavy metal removal

AbstractIn this work, two novel pyrimidine‐cored covalent organic frameworks TpTap‐COF and TpTan‐COF were synthesized for the first time and used for the adsorption of heavy metal ions in aqueous solution. Both COFs are nanofiber clusters with preferable crystallinity and thermal stability. The impact parameters such as pH value, shaking time, initial concentration, and temperature were studied by batch adsorption experiments in the multi‐metal ions system. The adsorption of six metal ions onto COFs follows the pseudo‐second‐order kinetic model and the Freundlich isotherm model, which is a chemical adsorption process that occurs on non‐uniform surfaces. The adsorption rate is determined by both film diffusion and intraparticle diffusion. Further research on the adsorption of copper ions onto COFs indicates the formation of metal complexes between O#N#N/O#O chelating sites in the COF skeleton and Cu ions through the sharing of lone pair electrons.

Ferroelectricity induced by lone pair electron effect in halide perovskite monolayers

Ferroelectricity induced by lone pair electron effect in halide perovskite monolayers

Synthesis, characterization and structure-property relations in mullite-type Pb2(Pb1−x Sn x )O4 solid solution

Abstract The crystal structures of both Pb2PbO4 (Pb3O4) and Pb2SnO4 at room temperature can be described using mullite-type setting in the space groups P42/mbc and Pbam, respectively. At what chemical extend the crystal structure prefers either of the space groups would be an excellent playground in the Pb2(Pb1−x Sn x )O4 solid solution. Members of the solid solutions have been prepared by solid-state reactions carried out in sealed quartz tubes. Each sample has been found to be phase pure confirmed by X-ray powder diffraction data Rietveld refinement. Samples with higher tin content require higher synthesis temperatures, and controlled decomposition of Pb3O4 serves as the source for both Pb2+ and Pb4+ cations. Since the Pb4+ cation is larger than Sn4+, the MO6 polyhedral volume decreases with increasing Sn-content. As such, each metric parameter shows a linear trend following Vegard’s rule. The concomitant contraction of the MO6 octahedra and the high stereo-chemical activity of the 6s 2 lone electron pairs of lead in the Pb2+O4 distorted pyramid results in symmetry reduction. DFT suggests dynamical instability of the tetragonal Pb3O4 while Pb2SnO4 keeps orthorhombic symmetry at low temperatures, which agrees well with the experimental findings. The global blue shift of the vibrational mode frequencies is explained by the quasi-harmonic approach. The indirect band-gap linearly increases from 2.1(1) eV (x = 0) to a maximum value of 2.5(1) eV for x = 0.8 followed by a sharp drop towards Pb2SnO4. Thermogravimetric analysis demonstrates higher thermal stability with increasing Sn-content, which is explained in terms of higher bond strength of Sn–O than that of Pb–O in the MO6 octahedra.

Gradual Increase in Birefringence of Antimony Oxalates through Precise Tuning of the Sb3+/[C2O4]2- Ratio.

Birefringent crystals play a crucial role in modulating and controlling the polarization of light in the optical communication and laser industries. Recently, adopting appropriate strategies to enhance the birefringence of crystals has become a prominent area of research focus. Herein, four UV antimony oxalate birefringent crystals, namely, K5Sb2(C2O4)5.5·3H2O, BaSb(C2O4)2.5·3H2O, Na4Sb2O(C2O4)4·6H2O, and Na3Sb(C2O4)2F2·2H2O, have been successfully synthesized. These compounds feature a similar zero-dimensional (0D) cluster structure and share the same functional groups, including π-conjugated [C2O4]2- groups and Sb3+-based distorted polyhedra with stereochemically active lone pairs (SCALPs). Interestingly, we achieved a stepwise increase in birefringence by precisely controlling the Sb3+/[C2O4]2- ratio, ultimately resulting in the compound Na3Sb(C2O4)2F2·2H2O exhibiting a large birefringence (0.21@546 nm). Additionally, we confirmed that the synergistic effects between the π-conjugated [C2O4]2- groups and the distorted polyhedra based on Sb3+ are responsible for the excellent optical properties observed in the reported compounds.