Raman and Infrared Studies of Platinum-Based Drugs: Cisplatin, Carboplatin, Oxaliplatin, Nedaplatin, and Heptaplatin

Abstract

This study reports the optimized structures and lowest-energy conformations/stereochemistry of five currently used platinum-based drugs: cisplatin, carboplatin, nedaplatin, oxaliplatin, and heptaplatin. Normal Raman and IR spectra of each drug are experimentally obtained and have been compared to various levels of density functional theory (DFT). Although some combination of structure, reactivity, or spectroscopy for these drugs has been studied by various groups, there are no known experimental normal Raman and IR spectra for nedaplatin, oxaliplatin, and heptaplatin in the literature. The detailed structural and vibration findings of these drugs are very important to understanding platinum behavior and drug dynamics. The following work explores the vibrational frequencies of these drugs particularly by focusing on the low-energy modes between 200 and 600 cm, where anharmonicity effects will have less influence on the accuracy of computed frequencies. Ideally, the Pt-N stretching modes provide vibrational diagnostics for each drug. Interestingly, a vibrational energy decomposition analysis (VEDA) suggests that oxaliplatin and heptaplatin Pt-N stretching modes are not Raman or IR active. Instead, C-C and Pt-O stretching frequencies in the various bidentate dioxo ligands might be more useful in characterizing new cisplatin derivatives. Analysis of anharmonicity effects was compared against (and in tandem with) dimer computations of four of the five drugs. Harmonic vibrational computations of the dimeric cisplatin derivatives provided greater qualitative improvement than that of the monomeric derivatives. Satisfying agreement with experimental Raman spectra was obtained, even without resorting to linear scale factors for the harmonic dimer frequencies.

Cisplatin interacting with buffering media and cysteine: Molecular insight due to Raman microspectroscopy

“…Figures a and S1 compare the Raman spectrum of cisplatin with that of cisplatin being dissolved in sodium perchlorate, sodium chloride, and/or Tris. Figure a shows the spectral region of 150–600 cm −1 , which has been proved for vibrational diagnostic of PtN stretching modes very recently . Figure S1 depicts the two other spectral regions of 600–1,750 cm −1 and 2,400–3,700 cm −1 for the purpose of a better peak visibility because Raman signal of complex inorganic compounds is more intensive in the low‐wavenumber region (metal‐related vibrations) than the signal stemming from the other parts of the complex compound …”

“…The structural parameters and vibrational results predicted by the calculations were compared with the corresponding experimental data, and a complete assignment of the cisplatin vibrational spectra was presented in Amado et al and Georgieva et al Later theoretical calculations of cisplatin vibrational modes were published in several studies . Quantum chemical calculations of cisplatin were discussed as a correct modeling approach in Tasinato et al The most recent study of the optimized structures and lowest energy conformations of five currently used platinum‐based drugs (cisplatin, carboplatin, nedaplatin, oxaliplatin, and heptaplatin) has focused on the low‐energy modes between 200 and 600 cm −1 , where anharmonicity effects have less influence on the accuracy of computed frequencies. Throughout this work, we use the vibrational assignment published in several studies …”

“…Quantum chemical calculations of cisplatin were discussed as a correct modeling approach in Tasinato et al The most recent study of the optimized structures and lowest energy conformations of five currently used platinum‐based drugs (cisplatin, carboplatin, nedaplatin, oxaliplatin, and heptaplatin) has focused on the low‐energy modes between 200 and 600 cm −1 , where anharmonicity effects have less influence on the accuracy of computed frequencies. Throughout this work, we use the vibrational assignment published in several studies .…”

Loading of Cisplatin into Mesoporous Silica Nanoparticles: Effect of Surface Functionalization

“…The Raman spectrum of cisplatin ( Fig. 9(a)) showed 4 vibration bands at 162, 255, 322 and 524 cm -1 that were respectively attributed to the skeletal in-plane deformation modes  Cl-Pt-Cl ,  N-Pt-N and the Pt-Cl ( Pt-Cl ) and Pt-N ( Pt-N ) stretching modes 75,76 . The Raman bands of CDDP were observed for all spectra, except for CDDP@MSNs-SH ( Fig.…”

C-demethylation and 1, 2-amino shift in (E)-2-(1-(3-aminophenyl) ethylidene)hydrazinecarboxamide to (E)-2-(2-aminobenzylidene)hydrazinecarboxamide and their applications

“…Their remarkable success has been marred somehow because of several side effects such as nephrotoxicity, adverse effects on the peripheral nervous system as well as liver damage, severe emesis and drug resistant tumors etc. 28 . Limitations of platinum based drugs arouse to design novel organic molecules as anticancer drugs.…”