Crystal structures, magnetic and non-linear optical properties of methoxyphenyl nitronyl–nitroxide radicals

Abstract

The three isomers (para, meta and ortho, hereafter denoted P, M and 0) of 2-(methoxyphenyl)-4,4,5,5-tetramethylimidazoline-1 -oxyl-3-oxide have been synthesized and their crystal structures solved.

Second harmonic generation in a molecular magnetic chain

“…The material has then high efficiency for SHG, only limited by the damage threshold. Pellets of the radical alone gave a SHG signal about three orders of magnitude lower [12], in agreement with reports of strong enhancement of the SHG due to supramolecular helical arrangement of molecular units [13]. This means that the arrangement of the units into chains can give rise to high chiral coefficients of the χ (2) tensor, on which the magnetic effect can be important.…”

Tetrathiafulvalene–Polychlorotriphenylmethyl Dyads: Influence of Bridge and Open‐Shell Characteristics on Linear and Nonlinear Optical Properties

“…Indeed, after the first example reported in 1998 by N. Martín, J. Garín and co‐workers, many other TTF‐based push–pull derivatives with closed‐shell electronic structures exhibiting large NLO responses have been described . On the other hand, molecular materials with open‐shell electronic structures have also aroused interest because of their high potentiality as NLO‐phores . Some of us previously reported the second‐order nonlinear optical (SONLO) response of a family of polychlorotriphenylmethyl (PTM) radical derivatives showing large β hyperpolarizability values .…”

“…[10][11][12][13][14][15][16][17][18] On the other hand, molecular materials with open-shell electronic structures have also aroused the interest of many researchers because of their high potentiality as NLO-phores. [19][20][21][22][23][24] Thus, a few years ago, some of us reported the second-order non-linear optical (SONLO) response of a family of polychlorotriphenylmethyl (PTM) radical derivatives showing large β hyperpolarizability values. [25][26][27] Interestingly, PTM radical derivatives can act as efficient electron acceptors in front of many donor molecules.…”

Evidence of intermolecular π-stacking enhancement of second-harmonic generation in a family of single chain magnets

“…This is in overall agreement with previously reported results on similar molecular systems, and especially p-substituted nitronyl-nitroxide (NIT) systems. 18,19 Studies in solution on differently substituted radicals have evidenced a molecular hyperpolarizability of the order of 3.6 ¡ 0.4 6 10 230 esu for p-substituted NIT systems, while a slightly better efficiency was detected for m-substituted ones in the crystalline phase. 18 The nonlinear optical properties of molecular systems are often interpreted in terms of charge-transfer (CT) processes, taking place between electron-rich and electron-deficient groups.…”

“…18,19 Studies in solution on differently substituted radicals have evidenced a molecular hyperpolarizability of the order of 3.6 ¡ 0.4 6 10 230 esu for p-substituted NIT systems, while a slightly better efficiency was detected for m-substituted ones in the crystalline phase. 18 The nonlinear optical properties of molecular systems are often interpreted in terms of charge-transfer (CT) processes, taking place between electron-rich and electron-deficient groups. 3 It is worthwhile to point out, anyway, that here the CT term does not refer to a true electron transfer between two stable states of the system.…”