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Chronic intermittent hypoxia plays an important role in the mechanism of various adverse reactions of obstructive sleep apnea syndrome (OSA). Epigenetic process participates in the occurrence and development of OSA and complications by affecting adaptive potential and phenotypic variation under chronic intermittent hypoxia. Therefore, understanding the effect of epigenetic regulation on OSA is helpful to provide new ideas for clinical phenotype and targeted therapy of OSA.

Three enantiomeric pairs of novel homochiral coordination compounds (HCCs) with the formula {[Zn( D -hpg)(4,4′-bipy)(H 2 O)] · (NO 3 )} n 1-D , {[Zn( L -hpg)(4,4′-bipy)(H 2 O)] · (NO 3 )} n 1-L , {[Zn( D -hpg)(4,4′-bipy)(H 2 O)] · (ClO 4 )} n 2-D , {[Zn( L -hpg)(4,4′-bipy)(H 2 O)] · (ClO 4 )} n 2-L , [Zn( D -hpg) 2 (4,4′-bipy)] · (4,4′-bipy) · 2H 2 O 3-D , [Zn( L -hpg) 2 (4,4′-bipy)] · (4,4′-bipy) · 2H 2 O 3-L ( D -Hhpg =  D -(−)-4-Hydroxyphenylglycine, L -Hhpg =  L -(+)-4-Hydroxyphenylglycine, 4,4′-bipy = 4,4′-bipyridine) have been synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, thermal analysis and powder X-ray diffraction. Compounds 1 and 2 are isostructural 2D layer structures with NO 3 – or ClO 4 – anions between the layers. While compound 3 features a 0D structure without counter anions. Compounds 1-D and 2-D both contain 1D right-hand helical chains via D -Hhpg ligand, while 1-L and 2-L both contain 1D left-hand helical chains via L -Hhpg ligand. It's worth noting that 3-D forms left-hand supramolecular double helical chains, while 3-L forms right-hand supramolecular double helical chains. Compounds 1 – 3 are further extended into 3D supramolecular architectures through hydrogen-bonding interactions. Circular dichroism and luminescent properties of compounds 1 – 3 were investigated at room temperature. Our results highlight that chiral ligands have an important effect on regulating the chirality/helicity of complexes and the frameworks can be controlled via applying different zinc salts and adjusting the pH values. [ABSTRACT FROM AUTHOR]