[论文解读] Efficient Calculation of Absorption Spectra of Platinum Complexes Used as Luminescent Probes for Cancer Detection

Lena T. T. Nguyen, Ernst D. Larsson+3 more|arXiv (Cornell University)|Feb 20, 2026

Metal complexes synthesis and properties被引用 0

一句话总结

该论文基准了 Pt(II) 托夹体在 Pt(II) pincer 配体的 UV–Vis 光谱的 TD-DFT 方法，分别在单体和嵌入 DNA 模型中的光谱表现，并建议使用带有分离函数的自旋-轨道耦合/时间自洽近似/RI 近似以提高准确性与效率。

ABSTRACT

Despite major advances in oncology, many chemotherapeutic agents still cause severe side effects that reduce quality of life, motivating new approaches for early detection and targeted elimination of cancer cells. Luminescent transition metal complexes are promising biomolecular probes, since intercalation between DNA base pairs significantly changes their luminescence. However, reliable computational protocols to predict optical properties of transition metal intercalators are limited, making accurate absorption spectra calculations essential for screening candidates. Here, we benchmark methods for computing UV-Vis spectra of a Pt(II) pincer complex. The complex is studied both in isolation and intercalated in a small DNA model, representing probes designed to target DNA-associated molecular abnormalities. We find that the largest source of uncertainty stems from the exchange-correlation functional and recommend range-separated hybrids for robust spectral predictions. The Tamm-Dancoff approximation (TDA) and the resolution of identity (RI) approximations provide significant speedups for TD-DFT with only a modest loss of accuracy. Since geometry optimization is often the dominant cost, PBEh-3c emerges as an efficient alternative to conventional DFT, introducing errors comparable to those from TDA. Tight-binding methods (GFN-xTB) offer further acceleration, but yield larger deviations in structures and UV-Vis spectra; thus, unless extensive optimization is required, PBEh-3c provides the best balance between accuracy and efficiency.

研究动机与目标

• Identify reliable computational protocols to predict absorption spectra of Pt(II) intercalators used as cancer-detection probes.
• Assess how intercalation in a DNA fragment affects spectra and structure.
• Evaluate the impact of exchange-correlation functionals, SOC, TDA, and RI on TD-DFT accuracy and efficiency.
• Propose efficient workflow combining structure optimization and excited-state calculations.

提出的方法

• Optimize Pt(OH)(terpy)+ in isolation and in a DNA-intercalated model using various functionals (HF-3c, PBEh-3c, PBE/def2-SVP, PBE0/def2-SVP, B3LYP/def2-SVP) with D3-BJ dispersion and water solvent via PCM.
• Intercalate the optimized complex into a 5′-CG-3′ DNA fragment and optimize with PBEh-3c; test different charges and structures.
• Compute UV–Vis spectra with TD-DFT using PBE0/x2c-SVPall as reference; test SOC, TDA, and RI variations; compare against lower-cost geometries (PBEh-3c, GFN-xTB).
• Evaluate effect of basis sets and RI; use 24 states (no SOC) and 79 states (with SOC) for spectra; smear with Gaussian (FWHM 0.3 eV).
• Use MAE/MSE of energies and intensities to compare methods; overlay structures and compute RMSD for geometry comparisons.

Figure 1 : The isolated Pt(II) model complex ( $\text{[}\text{Pt}\text{(}\text{OH}\text{)}\text{(}\text{terpy}\text{)}\text{]}\text{}{\vphantom{\text{X}}}^{\vphantom{\smash[t]{\text{2}}}\hphantom{\text{}}\text{+}}$ ) and the Pt(II) model intercalated in a double helical DNA fragment investigated in

实验结果

研究问题

• RQ1 How do different exchange-correlation functionals influence the predicted UV–Vis spectra for Pt(II) intercalators?
• RQ2 What is the impact of spin–orbit coupling on the spectral features of Pt(II) complexes, and is it essential for accurate predictions?
• RQ3 Can rapid structural optimizations (e.g., PBEh-3c, GFN-xTB) yield spectra close to higher-cost DFT optimizations?
• RQ4 Does intercalation in a DNA fragment cause predictable spectral shifts (e.g., red shift) that are captured by appropriate functionals?

主要发现

• Long-range corrected (range-separated) functionals are necessary for robust spectral predictions of Pt(II) intercalators.
• SOC significantly reshapes individual bands, making SOC essential for accurate spectra of Pt complexes.
• TDA and RI accelerate TD-DFT calculations with modest accuracy loss, enabling faster screening.
• PBEh-3c provides efficient geometry optimizations with errors comparable to TDA; tight-binding GFN1-/GFN2-xTB are much faster but less accurate.
• Intercalation yields spectral changes consistent with LMCT character; LC-PBE predicts a red shift upon intercalation, unlike PBE0.
• Overall, a workflow using SOC on PBEh-3c structures with TDA/RI is recommended for balance of accuracy and efficiency.

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