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Methanol soluble and stable guanosine octamers were successfully achieved via H-bond self-assembly. Through structural conformational design, we developed a new class of guanosine derivatives with modification on guanine (8-aryl) and ribose (2′,3′-isopropylidene). This unique design led to the formation of the first discrete G 8 -octamer with its structure characterized by single crystal X-ray diffraction, MS and NMR spectroscopy. The G 8 -octamer showed unique cation recognition properties, including the formation of a stable Rb + templated G-quadruplex. Based on this observation, further modification on the 8-aryl moiety was performed to incorporate a cross-layer H-bond or covalent linkage. Similar G-octamers were obtained in both cases with structures confirmed by single crystal X-ray diffraction. Furthermore, the covalently linked G-quadruplex exhibited excellent stability even in MeOH and DMSO, suggesting a promising future for this new H-bond self-assembly system in biological and material applications. 

Abstract A reverse‐binding‐selectivity between monovalent and divalent cations was observed for two different self‐assembly G₁₆‐hexadecamer and G₈‐octamer systems. The dissociation constant between G₄‐quadruplex and monomer was calculated via VT‐¹H NMR experiments. Quantitative energy profiles revealed entropy as the key factor for the weaker binding toward Ba²⁺compared with K⁺in the G₈‐octamer system despite stronger ion‐dipole interactions. This study is the first direct comparison of the G₄‐quartet binding affinity between mono and divalent cations and will benefit future applications of G‐quadruplex‐related research. Further competition experiments between the G₈‐octamer and 18‐crown‐6 with K⁺demonstrated the potential of this G₈system as a new potassium receptor. 

Abstract Due to the high oxidation potential between Au^Iand Au^III, gold redox catalysis requires at least stoichiometric amounts of a strong oxidant. We herein report the first example of an electrochemical approach in promoting gold‐catalyzed oxidative coupling of terminal alkynes. Oxidation of Au^Ito Au^IIIwas successfully achieved through anode oxidation, which enabled facile access to either symmetrical or unsymmetrical conjugated diynes through homo‐coupling or cross‐coupling. This report extends the reaction scope of this transformation to substrates that are not compatible with strong chemical oxidants and potentiates the versatility of gold redox chemistry through the utilization of electrochemical oxidative conditions.