Rational Design of Macrometallocyclic Trinuclear Complexes with Superior π-Acidity and π-Basicity

Abstract

Density functional theory (DFT) has been used to assess the π-acidity and π-basicity of metalorganic trimetallic macromolecular complexes of the type [M(µ-L)]3, where M ) Cu, Ag, or Au and L ) carbeniate, imidazolate, pyridiniate, pyrazolate, or triazolate. The organic compounds benzene, triazole, imidazole, pyrazole, and pyridine were also modeled, and their substituent effects were compared to those of the coinage metal trimers. Our results, based on molecular electrostatic potential surfaces and positive charge attraction energy curves, indicate that the metal-organic macromolecules show superior π-acidity and -basicity compared to their organic counterparts. Moreover, the metal-organic cyclic trimers are found to exhibit π-acidity and -basicity that can be systematically tuned both coarsely and finely by judicious variation of the bridging ligand (relative π-basicity imidazolate > pyridiniate > carbeniate > pyrazolate > triazolate), metal (relative π-basicity Au > Cu > Ag), and ligand substituents. These computational findings are thus guiding experimental efforts to rationally design novel [M(µ-L)] 3 materials for applications in molecular electronic devices that include metal-organic field-effect transistors and light-emitting diodes.

Phosphorescence sensitization via heavy-atom effects in d10 complexes

“…9 [13,14]. The same principle is applicable to these more benign (than Hg analogues) fluorinated coinage metal trimers, because we discovered that they also can complex arenes and sensitize their triplet emissions.…”

“…Because non-fluorinated coinage metal trimers are electron-rich, particularly gold compounds (Figs. 4, 5, 6), [4][5][6][7][8][9][11][12][13][14][15][16][17] such Au 3 species can complex and sensitize the triplet emission of electron-poor organic molecules such as perfluorinated arenes [8,9,11]. The color chromaticity can be easily improved in phosphors synthesized by the strategies in this section because the emission of the binary adducts is essentially the unperturbed T 1 emission of the arene.…”

Modeling the Deposition of Metal Atoms on a p-Type Organometallic Conductor: Implications for Stability and Electron Transfer

“…The simulations revealed that cyclo-[Au(μ-Pz)] 3 trimers act as good π-bases and so should be good models for p-type conductors in molecular electronics. 16 For example, we recently reported the synthesis, characterization and computational modeling of stacked trimers, [Ag(μ-Tz-(n-C 3 F 7 ) 2 )] 3 3 [Au(μ-Pz-(i-C 3 H 7 ) 2 )] 3 (Tz = triazolate), where the cyclo-[Au(μ-Pz)] 3 donor is a p-type conductor in a p-n blended material. 17 In addition, cyclo-[Au(μ-Pz)] 3 complexes have also been used in applications that exploit their catalytic redox activity, metallomesogenic character, and photonic properties.…”

“…7,16,29 In addition, we also compared the geometries obtained from B3LYP with the B3PW91 30,31 hybrid functional (results not presented in the article) using the same basis set, which gave similar geometries for coinage metal-trimer complexes. In light of the study of Buhl et al on the geometries of transition metal complexes with different DFT functionals, [32][33][34] we selected the B3LYP functional for the current study.…”

“…Although this gap is large (and likely overestimated by these hybrid DFT calculations), electron donating substituents on the pyrazolate ligand reduce the HOMO-LUMO gap and make the trimer a conductor. 16 Here, our primary concern is the change in electronic properties of the prototype structure of cyclo-[Au(μ-Pz)] 3 upon the coordination of typical electrode metals, M 0 . Figure 3 The reduction in HOMO-LUMO gap is a result of both lowering the LUMO energy and raising the HOMO energy.…”