Malaysian Journal of Analytical Sciences, Vol 27 No 2 (2023): 280 - 291

 

SYNTHESIS, CRYSTAL STRUCTURE, SPECTROSCOPIC CHARACTERISATION, AND PHOTOPHYSICAL PROPERTIES OF IRIDIUM(III) COMPLEX WITH PYRIDINE-FORMIMIDAMIDE ANCILLARY LIGAND

 

(Sintesis, Struktur Hablur, Pencirian Spekroskopi, dan Sifat Fotofizikal Kompleks Iridium(III) dengan Ligan Ansilari Piridina-Formimidamida)

 

Nurul Husna As Saedah Bain1, Noorshida Mohd Ali1,*, Yusnita Juahir1, Suzaliza Mustafar1, Mohammad Kassim2, Saifful Kamaluddin Muzakir@Lokman3, Bohari Mohd Yamin2, and Jean-Claude Daran4

 

1Chemistry Department,

Faculty of Science and Mathematics,

Universiti Pendidikan Sultan Idris,

35900, Tanjong Malim, Perak, Malaysia

2School of Chemical Sciences and Food Technology,

Faculty of Science and Technology,

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

3Faculty of Industrial Sciences and Technology,

Universiti Malaysia Pahang,

26300 Gambang, Pahang, Malaysia

4CNRS, LCC (Laboratoire de Chimie de Coordination),

Université de Toulouse,

UPS, INPT, 205, Route de Narbonne, F-31077 Toulouse, France

 

*Corresponding author: noorshida@fsmt.upsi.edu.my

 

 

Received: 11 November 2022; Accepted: 17 January 2023; Published:  19 April 2023

 

 

Abstract

A phosphorescent Ir(III) complex was synthesised between 2-(1H-1,2,4-triazol-1-yl)pyridine and Ir(III) dimer, [Ir(2,4-F2ppy)2(µ-Cl)]2, where ppy denotes 2-phenylpyridine by reflux method. The Ir(III) complex was fully characterised by FTIR, NMR, LC-MS, and UV-Vis absorption spectroscopic methods. The presence of a strong band at 2220 cm−1 due to ν(C≡N) was revealed by the IR analysis. Both pyridine and phenyl aromatic rings have C=N stretching band at 1598 cm−1     and C=C stretching bands at 1554    and 1400 cm−1, respectively. The 1H NMR spectrum showed signals in the aromatic range of δ 5.00–9.00 ppm corresponding to phenylpyridine protons. The 13C NMR spectroscopic data were consistent with the Ir(III) complex formula, which revealed 37 carbon signals. The Ir(III) complex displayed the ESI-MS spectrum at m/z = 823. The UV-Vis spectrum displayed a weaker and broader band (374 nm) in the visible region due to the spin-forbidden 3MLCT transitions. The X-ray crystallographic study revealed that the Ir(III) ion was coordinated to the pyridine-formimidamide ancillary ligand and two 2-(2,4-difluorophenyl)pyridine cyclometalating ligands in an octahedral geometry. Steady-state emission spectroscopy determined that the Ir(III) complex emitted blue-green light in dichloromethane solution at room temperature with the vibronic structure to the peak shape (l = 462 nm and 487 nm) due to the admixture of 3LC and 3MLCT character excited states.

 

Keywords: Ir(III) complex, formimidamide, ancillary ligand, phosphorescent, metal-to-ligand charge transfer

 

Abstrak

Kompleks Ir(III) berpendar fosfor disintesis antara 2-(1H-1,2,4-triazola-1-yl)piridina dan dimer Ir(III), [Ir(2,4-F2ppy)2(µ- Cl)]2 di mana ppy mewakili 2-fenilpiridina melalui kaedah refluks. Kompleks Ir(III) dicirikan sepenuhnya melalui kaedah spektroskopi: FTIR, NMR, LC-MS, dan penyerapan UV-Vis. Kehadiran satu jalur kuat pada 2220 cm−1 disebabkan oleh ν(C≡N) telah dikenal pasti daripada analisis IR. Kedua-dua gelang aromatik piridina dan fenil, masing-masing mempunyai jalur regangan C=N pada 1598 cm−1 dan jalur regangan C=C pada 1554 dan 1400 cm−1. Spektrum 1H NMR menunjukkan isyarat dalam julat aromatik δ 5.00–9.00 ppm sepadan dengan proton fenilpiridina. Data spektroskopi 13C NMR juga konsisten dengan formula kompleks Ir(III), yang menunjukkan 37 isyarat karbon. Kompleks Ir(III) menunjukkan spektrum ESI-MS pada m/z = 823. Spektrum UV-Vis mempamerkan jalur yang lebih lemah dan lebar (374 nm) di rantau yang boleh dilihat disebabkan oleh peralihan 3MLCT spin-terlarang. Kajian kristalografi sinar-X menunjukkan ion Ir(III) dikoordinasi kepada ligan ansilari piridina-formimidamida dan dua ligan siklometalasi 2-(2,4-diflorofenil)piridina dalam geometri oktahedral. Spektroskopi pancaran keadaan-stabil menunjukkan kompleks Ir(III) memancarkan cahaya biru-hijau dalam larutan diklorometana pada suhu bilik dengan struktur vibronik kepada bentuk puncak (l = 462 nm dan 487 nm) disebabkan oleh bauran ciri keadaan teruja 3LC dan 3MLCT.

 

Kata kunci: Kompleks Ir(III), Formimidamida, ligan ansilari, berpendar fosfor, pemindahan cas logam ke ligan

 

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