Fonksiyonel Koordinasyon Motifi Tasarımı: Nikotinamid-Co(II) Kompleksinin Yapısal ve Elektronik Özelliklerine İlişkin Bulgular

Öz

Nikotinamid içeren yeni bir kobalt(II) kompleksi sentezlenmiş ve yapısal olarak karakterize edilmiştir. Tek kristal X-ışını kırınımı, kompleksin triklinik P-1 uzay grubunda kristallendiğini ve Co(II) merkezinin iki nikotinamid ligandı ve dört su molekülü ile tanımlanan hafif bozulmuş bir oktahedral geometriye sahip olduğunu ortaya koymuştur. Birim hücrede bulunan tiyofen-2-karboksilik asit molekülleri, hidrojen bağları aracılığıyla yapıyı stabilize etmektedir. FT-IR, UV-Vis ve TGA analizleri koordinasyon çevresini, elektronik geçişleri ve termal davranışı doğrulamıştır. DFT hesaplamaları deneysel sonuçları desteklemiş ve hesaplanan HOMO–LUMO aralığı (4.40 eV) ile deneysel optik bant aralığının (4.32 eV) yakın uyum gösterdiği görülmüştür. Hirshfeld yüzey analizi, kristal paketlenmesinde hidrojen bağlarının ve π–π etkileşimlerinin belirleyici rolünü vurgulamıştır. Genel olarak bulgular, kompleksin yapısal ve elektronik özelliklerine ilişkin tutarlı bir açıklama sunmakta ve nikotinamid temelli sistemlerin koordinasyon kimyası ve fonksiyonel malzeme tasarımındaki potansiyelini ön plana çıkarmaktadır.

Anahtar Kelimeler

• Kobalt(II) kompleks
• nikotinamid
• tek-kristal XRD
• DFT

Designing Functional Coordination Motif: Structural and Electronic Insights from a Nicotinamide-Co(II) Complex

Öz

A new cobalt(II) complex containing nicotinamide has been synthesized and structurally characterized. Single crystal X-ray diffraction revealed that the complex crystallizes in the triclinic P-1 space group, with the Co(II) center surrounded by two nicotinamide ligands and four water molecules, forming a slightly distorted octahedral geometric arrangement. Thiophene-2-carboxylate anions in the unit cell are not ligands but anionic counterions, contributing to the stability of the structure through hydrogen bonds. The complex exhibits a broad absorption band in the 200-350 nm range, while a broad d-d transition band is observed in the 350-650 nm range. The electrochemical HOMO-LUMO gap was measured as 1.82 eV, while the theoretical band gap of 4.40 eV and the optical band gap of 4.32 eV were found to be quite close, and this result is in good agreement with the observed data. Hirshfeld surface analysis highlighted the fundamental role of hydrogen bonds and π–π interactions in crystal structures. The data obtained in this study contribute to the comprehensive understanding of the effects of non-coordinating counterions in cobalt(II)-nicotinamide systems and expand the knowledge base for the design of charged coordination compounds with broad application potential.

Anahtar Kelimeler

• Cobalt(II) complex
• nicotinamide
• single crystal XRD
• DFT

Kaynakça

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