Photophysical and electrochemical studies of multinuclear complexes of iron(II) with acetate and extended conjugated N-donor ligands.

Norbani Abdullah,Suhana Mohd Said,Afiq Azil,Abdul Rahman Nordin,Muhamad Faris Roslan,Anita Marlina

doi:10.1155/2015/860537

Abstract

A dimeric iron(II) complex, trans-[Fe2(CH3COO)4(L1)2] (1), and a trinuclear iron(II) complex, [Fe3(CH3COO)4(H2O)4(L2)] (2), were studied as potential dye-sensitised solar cell materials. The structures of both complexes were deduced by a combination of instrumental analyses and molecular modelling. Variable-temperature magnetic susceptibility data suggested that 1 was made up of 56.8% high-spin (HS) and 43.2% low-spin (LS) Fe(II) atoms at 294 K and has a moderate antiferromagnetic interaction (J = −81.2 cm−1) between the two Fe(II) centres, while 2 was made up of 27.7% HS and 72.3% LS Fe(II) atoms at 300 K. The optical band gaps (E o) for 1 were 1.9 eV (from absorption spectrum) and 2.2 eV (from fluorescence spectrum), electrochemical bandgap (E e) was 0.83 eV, excited state lifetime (τ) was 0.67 ns, and formal redox potential (E′(FeIII/FeII)) was +0.63 V. The corresponding values for 2 were 3.5 eV (from absorption spectrum), 1.8 eV (from fluorescence spectrum), 0.69 eV, 2.8 ns, and +0.41 V.

Highlights

Polypyridyl complexes of Fe(II) are currently attracting the attention of researchers as potential photosensitizers in dyesensitized solar cells (DSSC) [1,2,3]
We noted that the Fe(II) complexes reported as potential DSSC materials were mostly mononuclear
This paper reports the syntheses, structural deduction, and determinations of band gaps and excited state lifetimes of a dimeric iron(II) complex, trans[b[FFisee(23t((eCCtrHHad33CCecOOylOOox))44y(()HLst12y)O2r]y)l(4]1(-)L2a2,2n)󸀠]d-b(a2ip)tyr(riFniidugicunlreee)ar1)wi.rLaos1n((4IaI,)4b󸀠c-iobdmiesnp[3tlae,4txe, N2-bipyridyl dianion of a donor, Schiff while base, L2 was a multidentate N-donor 6-phenyl-N,N󸀠-bis-(1H-pyrrol-2

Summary

Introduction

Polypyridyl complexes of Fe(II) are currently attracting the attention of researchers as potential photosensitizers in dyesensitized solar cells (DSSC) [1,2,3]. These low-spin complexes have similar structures as the corresponding Ru(II) complexes [4,5,6,7,8,9] but are much cheaper, easier to prepare, and less toxic. The main objective of this paper was to establish a correlation between band gaps and excited state lifetimes with the nuclearity and spin states of a complex, and types of conjugated ligands (2,2󸀠-bipyridine versus Schiff base)

Objectives

Methods

Results

Conclusion