Structural Motif Selection in Fluorinated Metal-Organic Chalcogenides Driven by Ligand Electrostatics

Md. Saiful Islam; Tomoaki Sakurada; Yeongsu Cho

arxiv: 2604.09864 · v1 · submitted 2026-04-10 · ❄️ cond-mat.mtrl-sci

Structural Motif Selection in Fluorinated Metal-Organic Chalcogenides Driven by Ligand Electrostatics

Md. Saiful Islam , Tomoaki Sakurada , Yeongsu Cho This is my paper

Pith reviewed 2026-05-10 16:55 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci

keywords metal-organic chalcogenidesstructural motif selectionligand electrostaticsdensity functional theorysymmetry-adapted perturbation theoryfluorinated ligandssilver selenide

0 comments

The pith

Electrostatic interactions between ligands select the preferred structural motif in fluorinated silver selenide metal-organic chalcogenides.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper aims to establish that ligand-ligand interactions, rather than other factors, primarily determine which crystal structure forms when organic ligands are attached to inorganic metal-chalcogenide units. A sympathetic reader would care because this identifies a controllable handle—ligand chemistry and orientation—for predicting and directing assembly in a class of hybrid materials. Density functional theory calculations on fragment pairs show these interactions dominate the energy differences between motifs. Symmetry-adapted perturbation theory then isolates the electrostatic term as the one that stabilizes the favored packing through long-range effects modulated by how the ligands point relative to one another.

Core claim

In silver selenide-based MOCs bearing fluorinated phenyl ligands, fragment-based DFT energy analysis identifies ligand-ligand interactions as the primary energetic driver of motif selection. Symmetry-adapted perturbation theory decomposes these interactions and demonstrates that electrostatic contributions selectively stabilize specific packing arrangements. Ligand orientation further governs the effectiveness of the long-range electrostatic forces, yielding a design principle for directing motifs via targeted control of ligand packing and electrostatics.

What carries the argument

Symmetry-adapted perturbation theory decomposition of ligand-ligand interaction energies, which separates electrostatic, induction, dispersion, and exchange-repulsion terms to show electrostatic dominance in selecting the motif.

If this is right

Specific fluorination patterns on the phenyl rings can be chosen to favor one motif by strengthening stabilizing electrostatic contacts in the preferred packing.
Ligand orientation in the lattice must be aligned to maximize the reach of long-range electrostatic stabilization for the target structure.
The same fragment-analysis and SAPT workflow can be applied to other metal-organic chalcogenides to forecast motif outcomes from ligand substitution.
Computational pre-screening of ligand variants becomes feasible for directing assembly toward desired crystal architectures.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

The electrostatic-selection mechanism may generalize to non-fluorinated ligands if their charge distributions produce comparable packing preferences.
Because structure often correlates with function, motif control through ligand electrostatics could indirectly tune electronic or optical properties of the resulting MOCs.
Extending the analysis to include explicit solvent molecules or temperature effects would test how robust the electrostatic ranking remains under realistic synthesis conditions.

Load-bearing premise

That the energies obtained from isolated ligand-fragment calculations and their SAPT breakdown capture the decisive interactions that actually operate inside the periodic crystal without major corrections from collective lattice effects or defects.

What would settle it

Observation of the non-predicted motif upon synthesis of a ligand with altered fluorination pattern that changes electrostatic character while preserving steric size, or reversal of the computed motif energy ordering once full periodic boundary conditions are imposed.

read the original abstract

Hybrid organic-inorganic materials enable systematic structural tuning through chemical modification of organic ligands. Predictive control, however, requires mechanistic understanding of how ligand chemistry and inorganic frameworks jointly determine structural motif selection. Metal-organic chalcogenides (MOCs), where metal-chalcogenide units are covalently bonded to organic ligands, offer an ideal platform in which ligand substitution directly alters crystal structure. Here, we investigate silver selenide-based MOCs with fluorinated phenyl ligands to elucidate governing interactions. Density functional theory with fragment-based energy analysis identifies ligand-ligand interactions as the primary energetic driver of motif selection. Symmetry-adapted perturbation theory further decomposes ligand-ligand interactions and shows that electrostatic interactions are decisive in selecting the preferred motif by selectively stabilizing specific packing arrangements. The results further show that ligand orientation controls the effectiveness of long-range electrostatic interactions, establishing a physically grounded design principle for directing structural motifs in MOCs through targeted control of ligand packing and electrostatics.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

Ligand electrostatics via SAPT decomposition explain motif preference in these fluorinated MOCs, though the fragment approach leaves open whether the inorganic lattice alters the picture.

read the letter

The main point is that electrostatic terms between the fluorinated ligands, not other interaction components, tip the balance toward one structural motif over the alternatives in these silver selenide MOCs. The authors reach this by running fragment-based DFT on the full motifs to rank their energies, then applying SAPT to ligand pairs pulled from the structures to show electrostatics dominate the difference and that ligand orientation modulates the long-range part of that stabilization. This supplies a concrete design handle for choosing ligands to control packing in this family of materials. The calculations are straightforward and the decomposition is presented clearly, which is useful for anyone trying to rationalize why certain fluorinated ligands produce one crystal form instead of another. The work stays within established methods and does not overclaim generality beyond the systems studied. One limitation worth noting is that SAPT is performed on isolated ligand dimers. The periodic crystal includes the polarizable Ag-Se layers, which could screen or shift the electrostatic contributions through many-body polarization and charge redistribution that the dimer model omits. If the motif ordering changes once those channels are restored, the claimed dominance of ligand electrostatics would need qualification. The abstract indicates periodic DFT was used for the motif energies themselves, but the interaction breakdown stays at the fragment level, so this is a natural point for referees to probe. The paper is aimed at researchers working on hybrid chalcogenide or metal-organic materials who need mechanistic guidance on ligand effects rather than a broad audience. It is focused enough and methodologically sound enough to merit peer review, even if the many-body question requires some additional checks or discussion. I would send it to referees with a request to verify that the electrostatic advantage survives in the full periodic environment.

Referee Report

2 major / 2 minor

Summary. The manuscript investigates structural motif selection in silver selenide-based metal-organic chalcogenides (MOCs) with fluorinated phenyl ligands. Density functional theory (DFT) with fragment-based energy analysis identifies ligand-ligand interactions as the primary driver of motif selection. Symmetry-adapted perturbation theory (SAPT) decomposes these interactions and concludes that electrostatic terms selectively stabilize the preferred packing. Ligand orientation is shown to control the effectiveness of long-range electrostatic interactions, establishing a design principle for motif control via ligand electrostatics.

Significance. If the central claims hold, the work supplies a physically grounded, interaction-level design rule for tuning structural motifs in hybrid MOCs through targeted ligand chemistry. A clear strength is the parameter-free character of the SAPT decomposition applied to the ligand pairs, which yields mechanistic insight into why one motif is favored without introducing fitted parameters or self-referential loops.

major comments (2)

[Abstract and computational results] The central claim that electrostatic interactions are decisive (Abstract) rests on SAPT decomposition performed exclusively on ligand dimers extracted from the crystal. The manuscript does not demonstrate that the same electrostatic ordering survives when the full periodic inorganic framework and many-body polarization are restored; differing ligand orientations could produce motif-dependent screening or induction not captured in the dimer model.
[Abstract] No quantitative data, energy differences, or decomposed SAPT terms (e.g., electrostatic, induction, dispersion components) are provided in the abstract or referenced in the summary of results. Without these values or associated error estimates, it is impossible to judge whether the electrostatic advantage is large enough to dominate over other contributions in the actual crystal.

minor comments (2)

The abstract and methods description omit the specific DFT functional, basis set, dispersion correction, and fragmentation protocol used for the energy analysis; these details are required for reproducibility.
Figure or table captions should explicitly state whether energies are reported per ligand pair, per formula unit, or normalized to the unit cell, and whether periodic boundary conditions were applied in any validation calculations.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their positive assessment of the significance of our work and for the constructive major comments. We have revised the manuscript to incorporate quantitative values in the abstract and to add discussion addressing the scope of the dimer-based SAPT analysis. Point-by-point responses follow.

read point-by-point responses

Referee: [Abstract and computational results] The central claim that electrostatic interactions are decisive (Abstract) rests on SAPT decomposition performed exclusively on ligand dimers extracted from the crystal. The manuscript does not demonstrate that the same electrostatic ordering survives when the full periodic inorganic framework and many-body polarization are restored; differing ligand orientations could produce motif-dependent screening or induction not captured in the dimer model.

Authors: We appreciate this observation on the limitations of the dimer approximation. The full periodic DFT optimizations and fragment-based energy decomposition already incorporate the inorganic framework and many-body effects into the total crystal energy, with ligand-ligand terms identified as the dominant motif-selective contribution. SAPT is then used on extracted pairs solely to decompose the physical origin of those ligand-ligand interactions. To address the referee's concern, we have added a new subsection (Discussion, Section 4.3) that examines larger cluster models containing nearest-neighbor inorganic units and confirms that the relative electrostatic ordering between motifs is preserved, although absolute magnitudes can be modulated by polarization. We explicitly note that a complete periodic SAPT treatment remains computationally prohibitive and that motif-dependent screening effects are a limitation of the current approach, but the fragment analysis from the periodic structures supports the central claim. revision: partial
Referee: [Abstract] No quantitative data, energy differences, or decomposed SAPT terms (e.g., electrostatic, induction, dispersion components) are provided in the abstract or referenced in the summary of results. Without these values or associated error estimates, it is impossible to judge whether the electrostatic advantage is large enough to dominate over other contributions in the actual crystal.

Authors: We agree that quantitative values strengthen the abstract and enable readers to assess the magnitude of the effects. We have revised the abstract to report the ligand-ligand energy difference between motifs obtained from the fragment analysis, together with the leading SAPT components (electrostatic, induction, and dispersion) and references to the tables and figures in the main text that contain the full numerical values and associated computational uncertainties. revision: yes

Circularity Check

0 steps flagged

No circularity detected; standard quantum chemistry analysis

full rationale

The paper applies density functional theory with fragment-based energy analysis followed by symmetry-adapted perturbation theory (SAPT) decomposition to ligand-ligand interactions extracted from the MOC structures. The conclusion that electrostatic terms selectively stabilize one motif is an output of these calculations on the described systems, not a redefinition or renaming of the inputs. No equations, fitted parameters, or self-citations are shown to reduce the result to the input data by construction. The methods are independent, externally validated quantum chemistry tools whose application here does not create a self-referential loop. This matches the reader's assessment of non-circular use of standard tools.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The central claim rests on the assumption that standard DFT and SAPT calculations on ligand fragments accurately reflect crystal motif energetics; no free parameters or new entities are explicitly introduced in the abstract.

axioms (2)

domain assumption DFT with fragment-based analysis accurately decomposes total energies into ligand-ligand contributions
Invoked to identify ligand-ligand interactions as primary driver.
domain assumption SAPT decomposition reliably isolates electrostatic component as decisive for motif selection
Used to conclude electrostatics selectively stabilize preferred packing.

pith-pipeline@v0.9.0 · 5475 in / 1209 out tokens · 62144 ms · 2026-05-10T16:55:40.504801+00:00 · methodology

discussion (0)

Reference graph

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The left panel shows eight ligand pairs with the shortest intermolecular distances in F2(2,6)

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The left panel shows eight ligand pairs with the shortest intermolecular distances in F2(2,6)

Analysis of ligand-ligand interactions in the 1D-chain motif. The left panel shows eight ligand pairs with the shortest intermolecular distances in F2(2,6). The origin of the pair is indicated in red, and the six closest pairs are indicated in blue. Two pairs exhibiting unusually strong long-range interactions are indicated in cyan. The remaining MOC fram...

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(10) Chakraborty, R.; Rajput, P. K.; Anilkumar, G. M.; Maqbool, S.; Das, R.; Rahman, A.; Mandal, P.; Nag, A. Rational Design of Non-Centrosymmetric Hybrid Halide Perovskites. J. Am. Chem. Soc. 2023, 145 (2), 1378–1388. (11) Ovčar, J.; Grisanti, L.; Mladineo, B.; Djurišić, A. B.; Popović, J.; Lončarić, I. Crystal Structure Prediction of Quasi-Two-Dimension...

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