Designing a Strong Second-Harmonic Generation Polar Iodate by the Structure-Directing Properties of the “Tumbler-like” [Zn(IO₃)(I₂O₅(OH))] Polyanions

Abstract

Materials with second-harmonic generation (SHG) properties have attracted great attention in the field of photon technology. However, synthesis of materials with strong SHG responses and polar structure still faces enormous challenges. Herein, a new iodate K 2 Zn(IO 3 ) 3 (I 2 O 5 (OH))-(IO 2 (OH))(H 2 O) (KZIOH) was synthesized by coupling distorted ZnO 6 octahedra with three diverse asymmetrical chromophores to assemble "tumbler-like" clusters, [Zn(IO 3 )-(I 2 O 5 (OH))], which was the first noncentrosymmetric (NCS) and polar iodate containing isolated [IO 3 ], [I 2 O 5 (OH)], and [IO 2 (OH)]. KZIOH exhibits the strongest SHG response (∼12 × KH 2 PO 4 (KDP)@1064 nm) among the polyiodates with two or more types of isolate units and a short ultraviolet cutoff edge (262 nm). It also possesses a moderate birefringence (0.055@532 nm) and a wide band gap (4.0 eV), indicating KZIOH is a promising SHG material. Theoretical calculations and crystal structure analysis show that the asymmetric and top-heavy configurations of I−O groups around Zn-centered octahedral units with the aid of hydrogen bonding favor its polar structure and strong SHG response.

Two Acentric Zn-Based l-Tartrates with Moderate Second Harmonic Generation Responses and Large Birefringence

“…Figures S8 and S9 present the IR spectra of the two title compounds. Both of them display broad absorption peaks near 3200 cm –1 associated with water molecules. , The absorption bands from 1238 to 1585 cm –1 could be assigned to the asymmetric stretching of CO and C–O bonds. , The IR spectrum of Zn-LTS shows the asymmetric and symmetric stretching vibrations of [SO 4 ] group near 1293 cm –1 . − The absorption bands in the range of 780–516 cm –1 can be assigned to the vibration of Zn–O bonds. − …”

From ZnF2 to ZnF2(H2O)4: Partial Substitution Achieves Structural Transformation and Nonlinear Optical Activity while Keeping Short Ultraviolet Cutoff Edge

“…Here, we chose ZnF 2 as the parent compound. On the one hand, fluorides tend to have a large band gap, corresponding to a low UV cutoff wavelength due to the largest electronegativity of F atom. − On the other hand, the polyhedron of Zn 2+ with d 10 electron configuration is prone to second-order Jahn–Taylor distortion, which is more likely to form an NCS structure, and then produce the SHG effect. − In addition, based on previous reports, we also know that Zn-containing oxyhalides mostly reach short UV cutoff edges. Such compounds as RbZn 2 BO 3 Br 2 (214 nm), KZn 2 BO 3 Cl 2 (194 nm), and NH 4 Zn 2 BO 3 Cl 2 (190 nm) were reported to confirm this idea.…”

Exploring a new short-wavelength nonlinear optical fluoride material featuring unprecedented polar cis-[Zr6F34]10− clusters

“…Wu’s group proposed a polar iodate K 2 Zn(IO 3 ) 3 (I 2 O 5 (OH))(IO 2 (OH))(H 2 O) composed of “tumbler-like” [Zn(IO 3 )(I 2 O 5 (OH))] clusters. 27 Luo’s group reported one DUV crystal Ba(SO 3 CH 3 ) 2 , with a new polar non-π-conjugated NLO building unit, SO 3 CH 3 − . 28 Wu’s group synthesized Zn(NH 3 )CO 3 which displays a “three-in-one” NLO-active motif which includes a polar NH 3 molecule, polar displaced Zn 2+ , and π-conjugated CO 3 2− ions.…”