Compared to pure organic amphiphiles, metalloamphiphiles display distinctive features, including luminescence, magnetism and catalytic properties. However, the self-organization of metalloamphiphiles is commonly driven by solvophobic effects. Alkyl chains and oligomeric ethylene glycol moieties are thus the most frequently used aggregation units to drive the self-assembly of metalloamphiphiles. We expect novel metallo-supramolecular structures with exciting functions to be created if additional noncovalent interaction modes are incorporated. In this work, a new type of metalloamphiphile, consisting of a Tb(III) complex head and a cholesteryl unit (TbL3+(I)), was designed and synthesized. TbL3+(I) spontaneously self-assembles into helical nanofibers (d = 6 nm) in water. This synthetic multivalent nanoscale binding array displays powerful capability for the recognition of DNA conformations through a turn-on luminescence sensing mechanism. ssDNA-kit1 triggered a 26-fold increase in the luminescence intensity of TbL3+(I). Its corresponding G-quadruplex structure (G-quadruplex-kit1), however, induced a 6.6-fold enhancement under the same conditions. Consequently, TbL3+(I) nanofibers can monitor DNA folding. In contrast, neither ssDNA-kit1 nor G-quadruplex-kit1 markedly promoted the luminescence of molecularly dispersed TbL3+(II), illustrating that the multivalent electrostatic interactions between the phosphate groups on the backbone of DNA and TbL3+(I) self-assembled into nanofibers could greatly improve the efficiency of the energy transfer between the guanine units and the organized TbL3+(I). The TbL3+(I) nanofibers could bind and distinguish not only the kit1-ssDNA/G-quadruplex but also the conformations of other G-rich DNA, such as spb1, htelo, and intermolec-htelo. The self-assembly of luminescent metalloamphiphiles thus provides a general and convenient strategy for the efficient recognition and conversion of molecular information.

Low-molecular-mass gelators and relevant molecular gels have been employed for water purification owing to their convenience and efficiency, but the process is time consuming due to low extraction efficiency originated from limited contact of the two phases. In this work, two novel di-cholesterol-based gelators, 1 and 2, with a ferrocenyl unit were synthesized and the gels based on 2 possess a smart thixotropic property. In particular, 2/heptane gel, the shear force induced phase transition is fast (within seconds) and fully reversible without the need of heating–cooling cycle. Based upon the thixotropic molecular gel, a novel separation strategy, which combines the great efficiency of liquid–liquid extraction and the convenience of liquid–solid separation, has been successfully conducted for removing iodine from wastewater. It was demonstrated that iodine was removed within several minutes and the extraction efficiency (72%) was the same with the one using corresponding liquid. Furthermore, 2/heptane gel is also responsive to chemical oxidation and variation in temperature. FTIR, NMR, CD and XRD studies revealed that helical fibers were formed via intermolecular hydrogen bonding and van der Waals interaction. It is believed that the results presented in this work are of importance for extending real-life applications of molecular gels.

A novel amphiphilic Tb3+ complex (TbL3+(I)) consisting of a +3 charged head and a hydrophobic alkyl chain has been developed. It spontaneously self-assembles in water and forms stable vesicles at neutral pH. TbL3+(I) has no aromatic groups (functioning as an antenna), and its intrinsic luminescence is thus minimized. These features lead to the self-assembling TbL3+(I) receptor molecules demonstrating an increased luminescence intensity upon binding of nucleotides. Upon addition of guanosine triphosphate (GTP), the luminescence from Tb3+ was notably promoted (127-fold), as the light energy absorbed by the guanine group of GTP was efficiently transferred to the Tb3+ center. In the case of guanosine diphosphate (GDP) and guanosine monophosphate (GMP), respectively, 78-fold and 43-fold increases in luminescence intensity were observed. This enhancement was less significant than that observed for GTP, due to fewer negative charges on GDP and GMP. No other nucleotides or the tested nonphosphorylated nucleosides affected the luminescence intensity to any notable extent. In marked contrast, all tested nucleotides, including guanine nucleotides, barely promoted the luminescence of molecularly dispersed receptors, TbL3+(II), indicating that the confinement and organization of molecules in a nanointerface play vital roles in improving the performance of a sensing system. This Tb3+ complex nanointerface is successfully used for monitoring the GTP-to-GDP conversion.Keywords: luminescent probes; molecular recognition; nanointerface; nucleotides; terbium complex