Haozhen Liu,Shiyu Du,Paipai Zhang,Jiawei Zhao,Yanna Chen,Donghai An
A high-performance ultraviolet (UV) nonlinear optical (NLO) material requires three essential characteristics: a short UV absorption edge, a strong secondharmonic generation (SHG) response, and favorable NLO coefficients. In this study, a novel rare-earth borate compound with the formula K 7 MgY 2 (B 5 O 10 ) 3 was successfully synthesized using a high-temperature solution method combined with chemical cosubstitution. The crystal adopts a non-centrosymmetric (NCS) structure (space group R32) and exhibits an SHG intensity 1.3 times that of potassium dihydrogen phosphate (KDP) under 1064 nm laser irradiation. Its UV cutoff edge is determined to be 290 nm, demonstrating exceptional potential for UV optical applications. Combined experimental and theoretical analyses reveal that the synergistic interplay between polarizable [B 5 O 10 ] groups and heterovalent K + /Mg 2+ /Y 3+ substitution underpins its superior NLO performance.
Seven undescribed C 27 steroidal glycosides , Seladelicatulasine A–G, including six cholestanol glycosides and one spirostanol glycoside, were isolated from Selaginella delicatula. Their structures were elucidated by 1D/2D NMR spectra and HRESIMS analyses. The absolute configurations of the sugars were determined by enzymatic hydrolysis and GC/MS analyses. These cholestanol glycosides were isolated from the family Selaginellaceae for the first time. Seladelicatulasine F is characterized as a rare B-5,6-secosteroid. In addition, all the compounds were evaluated for their inhibitory activities against cholinesterase (AChE/BChE) and monoamine oxidase (MAO-A/MAO-B). These steroidal glycosides displayed selective inhibition activities on cholinesterase. Seladelicatulasine A, B and E inhibited the AChE activity with IC 50 values of 0.31, 0.09, and 0.04 μ M, respectively. Seladelicatulasine A and F showed the strongest inhibition activity on BChE with IC 50 values of 0.37 and 0.65 μ M, respectively.
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