No abstract

Large birefringence (∆n = 0.277 at 546 nm) and strong second-harmonic generation (SHG) intensity (4.3 × KDP) achieve remarkable balance among a potential ultraviolet nonlinear optical crystal, 2(C3H7N6)+·2Cl-·H2O. Results of...

No abstract

Discovery of new nonlinear optical (NLO) crystals, especially crystals that can produce coherent light in the deep-ultraviolet (DUV) region is essential for the development of diverse fields. Here, we successfully discovered and synthesized a new DUV transparent NLO crystal KMg(H 2 O)PO 4 (KMP) using KTiOPO 4 (KTP) as a template through substituting TiO 6 by the MgO 5 (H 2 O) group. Its structure constructed by 2D [MgPO 5 ] ∞ infinite layers in which PO 4 groups arrange orderly leads to KMP exhibiting a large second harmonic generation (SHG) efficiency (≈1.14 × KDP) which is similar to KBe 2 BO 3 F 2 (1.2 × KDP). Moreover, the ultraviolet cut-off edge of KMP is blue-shifted to <200 nm from 350 nm of KTP after replacing the transition metal cations Ti 4+ by alkaline-earth metal cations Mg 2+ . First principle calculations reveal that the SHG efficiency of KMP was significantly contributed by PO 4 groups, and contributions from cations are negligibly small which agrees well with the anion group theory.

First cyclotetraphosphate as a nonlinear optical crystal with moderate second-generation harmonic response and short absorption edge.

Organic-inorganic hybrid nonlinear optical (NLO) materials have drawn increasing attention, which incorporates the suitable physicochemical characteristics of inorganic compounds with the excellent optical performance of organic molecules. Herein, a novel...

No abstract

Exploring the moisture-insensitive catalysis system for the ring-opening polymerization of cyclic esters is very valuable for the synthesis of polyesters in industry. To reduce metal residue in final polymers, using ppm-level catalysts for the moisture-insensitive and controllable ROP system is still a big challenge until now. In this work, as a general strategy, a series of D 3 symmetrical binuclear yttrium phenoxides were applied in the moisture-insensitive ringopening polymerization of rac-lactide. The structures of these yttrium complexes can be reversibly switched between highly active and less active species in the presence of water via changing temperature. These catalysts are so robust in air, the loading of catalyst can be as low as 15 ppm, and one molecular catalyst can mediate the synthesis of more than 1000 polymer chains. The low initiation efficiency of water was proved unambiguously; hence, the polymerizations are controllable with a highly efficient initiator of alcohol in moisture condition, and the high molecular weight of polylactide can reach 78.0 kg/mol. What is more, this moisture-insensitive system can show some heteroselectivity in the ROP of rac-lactide.