Simple synthetic procedure (reactions between iridium trichloride hydrate with a series of fluorine substituted 2-phenyl-N-methyl-benzimidazole derivatives L) leads to the cyclometallated Ir(III) complexes IrL2(acac) and IrL2(pic) where acac = acetylacetonate and pic = α-picolinate anions, respectively. All the investigated complexes exhibit strong absorption in the UV region, due to the spin allowed intra-ligand (IL) transitions, and moderately intense bands in the visible region, due to the metal-to-ligand-charge-transfer (MLCT) transitions. The complexes exhibit also strong luminescence in the deoxygenated 1:1 acetonitrile/dioxane solutions at 298 K as well as in the butyronitrile glasses at 77 K. In both experimental conditions the structured emissions (with the 0–0 transition within the 480–510 nm range of UV-Vis radiation) have been observed. Cyclic voltammetry investigations point out to reversible character of the electrochemical reactions leading to stable IrL2(acac)+ or IrL2(pic)+ cations and IrL2(pic)− anions. The corresponding IrL2(acac)− species have been found to be unstable under the applied experimental conditions (1:1 acetonitrile/dioxane solutions containing 0.1 M (C4H9)4NPF6 as the supporting electrolyte) most probably due to the irreversible electrochemical reduction of the acac− ligand. Appropriate combination of the electrochemical and luminescence properties found for the investigated complexes allows for the electron transfer generation of the excited 3∗IrL2(pic) and 3∗IrL2(acac) species. Triple-potential-step technique was used to create electrochemiluminescence (ECL) emission by annihilation of the electrochemically generated IrL2(acac)+ or IrL2(pic)+ cations and 4,4’-dicyano-biphenyl radical anion. Very high ECL emission efficiencies (close to the excited 3∗IrL2(acac) and 3∗IrL2(pic) luminescence yields) have been found.
采用简单的合成方法(在含氯化铱三水合物的溶液中与一系列氟取代的2-苯基-N-甲基苯并咪唑衍生物L反应),制备出环金属化的Ir(III)配合物IrL2(acac)和IrL2(pic),其中acac =乙酰丙酮和pic =α-吡啶酸根离子。所有研究的配合物在紫外区域表现出强烈的吸收,由于自旋允许的配体内部(IL)跃迁,以及在可见区域中表现出适度强的吸收,由于金属到配体的电荷转移(MLCT)跃迁。这些配合物在去氧的1:1乙腈/二恶烷溶液(298 K)以及77 K的丁腈玻璃中也表现出强烈的发光。在这两种实验条件下,观察到结构化的发射(在480-510 nm的紫外-可见辐射范围内的0-0跃迁)。循环伏安法研究指出,电化学反应具有可逆性,导致稳定的IrL2(acac)+或IrL2(pic)+阳离子和IrL2(pic)−阴离子。在实验条件下(1:1乙腈/二恶烷溶液,含0.1 M(C4H9)4NPF6作为支持电解质),发现相应的IrL2(acac)−物种不稳定,这很可能是由于acac−配体的不可逆电化学还原所致。对于所研究的配合物发现的电化学和发光性质的适当组合,可以产生激发的3∗IrL2(pic)和3∗IrL2(acac)物种的电子转移。采用三电位步进技术,通过电化学产生的IrL2(acac)+或IrL2(pic)+阳离子和4,4'-二氰基联苯自由基阴离子的消除,产生电化学发光(ECL)发射。发现非常高的ECL发射效率(接近激发的3∗IrL2(acac)和3∗IrL2(pic)发光产率)。