Complementary coordination of two predesigned 2,2':6',2″-terpyridine-based ligands to a Zn ion led to the exclusive formation of a heteroleptic bis(terpyridine) complex under ambient conditions. This highly self-selective process was facilitated by 9-anthracenyl substituents at the 6,6″-positions of a terpyridine, which not only decelerated the formation rate of its homoleptic complex, but also provided π-stacking stabilization in the heteroleptic complex. Facile construction of metallo-supramolecular poly(3-hexylthiophene) (P3HT)-block-poly(ethylene oxide) (PEO) diblock copolymers was realized using the complementary ligand pair. The morphological studies of the amphiphilic block copolymers in solution were conducted by atomic force microscopy and transmission electron microscopy, indicating that the self-assembled core-shell morphology such as spherical and fibrillar nanostructures could be controlled by adjusting the rod-coil block ratios. The heteroleptic complexes residing at the junction between two polymer blocks could be readily dissociated by EDTA to afford the unshelled P3HT nanofiber networks, and restored by treatment of bifunctional Zn-terpyridine-capped PEO to redisperse the aggregates. The presented supramolecular methodology highlights the merits of complementary metal-ligand coordination, and offers a new approach to engineering nanostructures assembled from rod-coil block copolymers.

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Frequency shift keying (FSK) signal has been widely used in modern radar systems. To intercept the FSK radar signal with a high interception probability, radar reconnaissance receiver should have an ultra-wideband receiving ability. The Nyquist folding receiver (NYFR) is a novel non-cooperative ultra-wideband receiver and it requires a small amount of equipment. When the FSK radar signal is intercepted by the NYFR, the corresponding output is a hybrid modulation signal. Therefore, it is necessary to investigate the parameter estimation of FSK radar signal intercepted by the NYFR. Herein, based on the NYFR using sinusoidal frequency modulation local oscillator (LO), the drawbacks of several existing parameter estimation methods are first analysed. To overcome these drawbacks, the NYFR architecture is improved by changing the LO modulation type to periodic linear frequency modulation. Then, based on the improved NYFR, a novel parameter estimation approach is proposed according to the LO modulation characteristics and the template matching rule. The proposed method is suitable for different kinds of common FSK radar signal code schemes and its computational load is low. At last, several simulation results show the merits of the proposed method.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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