How To Maximize Birefringence and Nonlinearity of π-Conjugated Cyanurates

Abstract

Materials with large birefringence (Δn) are highly needed by fiber-optic isolators, whereas crystals showing strong second-order harmonic generation (SHG) are the key component for all-solid-state laser devices. Cyanurate constructed by the planar π-conjugated ring (C 3 N 3 O 3 , CY) is a class of fascinating materials exhibiting not only very large Δn (larger than that of calcite) but also strong SHG (2 times that of β-BaB 2 O 4 , BBO). Here, we report five new cyanurates (I−V) and their single-crystal structures; among them, II realizes a Δn = 0.4, the maximum in the cyanurate family, and IV realizes a d 33 = 6.69 pm/V, one of the highest values in the cyanurate family. We discover a dependence between Δn and the coplanarity of the CY rings that is explicitly described by a Boltzmann function, in which the coplanarity is defined by the dihedral angle (γ) between the CY plane and the principal optical axes XY plane. II realizes the maximum Δn due to its zero γ that indicates perfect coplanarity. Such a Δn−γ dependence also allows the Δn prediction of cyanurates. Furthermore, we uncover that the SHG intensity of cyanurates increases monotonically as the angle (θ) between the maximum hyperpolarizability (β max ) vector and the crystal 2 1 polar axis decreases. We predict the d ij to extend well beyond such a value and to maximize at θ = 0°. Our results have significant implications for the future rational design and discovery of highperformance materials of π-conjugated and other related systems.

LiGaF2(IO3)2: A mixed-metal gallium iodate-fluoride with large birefringence and wide band gap

“…Generally, two types of oxide-based units with large macroscopic anisotropic mainly contribute to the birefringence: planar π-conjugated anions and second-order Jahn-Teller (SOJT) distorted cations. The former type is widely studied like metal cyanurates, borates and borate derivatives [14][15][16][17][18][19][20][21][22]. Cyanurates contain a considerable polarization unit with large birefringence and short absorption edge [17][18][19][20][21][22].…”

An Exceptional Peroxide Birefringent Material Resulting from d–π Interactions

“…[13] In particular, Sn 2 B 5 O 9 Cl [13] exhibits a remarkable enhancement of 16 times as compared with the isostructural Ba 2 B 5 O 9 Cl. It is of great importance and current interests to develop new strategies for birefringent materials.With a few exceptions, [14] to date birefringent materials are almost exclusively limited to oxides. In comparison, the possibility of peroxides as birefringent materials has long been overlooked, despite the fact that their localized conjugated p orbitals is highly polarizable.…”

“…With a few exceptions, [14] to date birefringent materials are almost exclusively limited to oxides. In comparison, the possibility of peroxides as birefringent materials has long been overlooked, despite the fact that their localized conjugated p orbitals is highly polarizable.…”

Two Light‐Metal Dihydrogenisocyanurate Hydrates Linked by Diagonal Relationship: Syntheses, Crystal Structures, and Vibrational Spectra of Li[H2N3C3O3]·1.75 H2O and Mg[H2N3C3O3]2·8 H2O

“…To the best of our knowledge, a plethora of alkali-and alkaline-earth metal cyanurates or cyanurate hydrates have been reported and characterized, [3][4][5][6][7][8][9][10][11] but the monoclinic compound Li 2 [HN 3 C 3 O 3 ]•2 H 2 O was the only one containing only Li + or Mg 2+ , respectively. Exploiting a review paper by Seifer, [12] we started to reproduce the reported synthesis for lithium and magnesium cyanurates in order to elucidate, if the diagonal relationship prevails under these conditions or if the general trend of "the higher the charge-to-radius quotient is, the more ARTICLE hydrated the cation becomes", will be confirmed.…”