An investigation on the second-order nonlinear optical response of cationic bipyridine or phenanthroline iridium(iii) complexes bearing cyclometallated 2-phenylpyridines with a triphenylamine substituent

Abstract

The synthesis and characterisation of six new cationic iridium(iii) complexes bearing either 4,4'-di-tert-butyl-2,2'-bipyridine (dtBubpy) or 5-NO2-1,10-phenanthroline along with two cyclometallated 2-phenylpyridine derivative ligands, decorated with triphenylamine groups either meta or para to the Ir-CC^N bond or para to the Ir-NC^N bond, are reported. The second-order nonlinear optical (NLO) properties of all the compounds have been determined by the electric field induced second harmonic generation technique and show that the μβEFISH value can be tuned by the nature of the iridium coordination sphere. The dipole moment, μ, necessary to evaluate the quadratic hyperpolarizability βEFISH, was theoretically determined. The linear optical properties of the complexes are also presented and rationalised by quantum-chemical calculations. One of the prepared iridium compounds was incorporated into a polystyrene film, affording the first example of a second-order NLO active polymeric film based on a cationic organometallic complex.

A trip in the nonlinear optical properties of iridium complexes

“…The µβ values of these six complexes were determined by the EFISH method working in CHCl 3 ; the dipole moments of the complexes were calculated with the Polarizable Continuum Model-Density Functional Theory (PCM-DFT), allowing determination of the quadratic hyperpolarizability (Table 7) [87]. overcomes the reduction of µ that is due to the more symmetric arrangement of the donor groups around the iridium(III) centre [87].…”

“…The µβ values of these six complexes were determined by the EFISH method working in CHCl 3 ; the dipole moments of the complexes were calculated with the Polarizable Continuum Model-Density Functional Theory (PCM-DFT), allowing determination of the quadratic hyperpolarizability (Table 7) [87]. overcomes the reduction of µ that is due to the more symmetric arrangement of the donor groups around the iridium(III) centre [87]. The compounds with 5-NO 2 -1,10-phenanthroline (25b, 26b, 27b) have a smaller dipole moment than the related complexes with 4,4'ditertbutyl-2,2'-bipyridine but they have a higher µβ 1.907 (EFISH) value due to an increase of β 1.907 (EFISH) caused by the electron-withdrawing strength of this phenanthroline (Table 7).…”

“…The dispersed in a PMMA or polystyrene (PS) matrix, and oriented by corona poling, were also studied [87]. The SHG signal of films in PMMA decreased rapidly because of the loss of orientation of the chromophores when the electric field was switched off, whereas a good stability was obtained with PS.…”

Cyclometalated Ir(III) Complexes with Curcuminoid Ligands as Active Second-Order NLO Chromophores and Building Blocks for SHG Polymeric Films

“…Indeed, they can reach µβ values (β is the projection along the ground state dipole moment (µ) axis of the vectorial component of the tensor of the quadratic hyperpolarizability) superior to 500 × 10 −48 esu, making them competitive with respect to organic along the ground state dipole moment (μ) axis of the vectorial component of the tensor of the quadratic hyperpolarizability) superior to 500 × 10 −48 esu, making them competitive with respect to organic compounds and of interest for optoelectronic applications [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Among them, photoactive iridium complexes are very appealing not only for their attractive second-order NLO properties [27,[32][33][34][35][36][37], but also because they find application in various fields, including in electroluminescent devices [38][39][40][41], in dye-sensitized solar cells [41][42][43][44][45], in sensing [41], as two-photon absorption reagents for high image resolution [46][47][48][49][50], as bioimaging probes [41,[51]…”

A Nonlinear Radio-photon Conversion Device

“…An interesting subclass of the considered category of materials is the so-called metalorganic frameworks (MOF) [14][15][16][17]. In MOFs not only the organic filler is responsible for the macroscopic properties (see [13]), but also the metal structure, which, besides the structure strength (which was laid in the original idea of developing the MOF), can also form a field potential when irradiated with an electromagnetic field of the corresponding frequency range [14,18].…”