Spatial organization of chromophores is of crucial importance in governing energy-transfer processes and hence the performance of devices that exploit such energy flows. Studying EET processes in systems with the donor and acceptor connected by covalent bonds has provided most of the fundamental advances in this field. 14,16 However, with the evolution of energy-transfer systems toward increasingly large, sophisticated donor−acceptor assemblies, the reliance on covalent linking becomes increasingly untenable. 17 Noncovalent interactions, including van der Waals, hydrophobic, π−π, dipole, and metal ligation, may provide limitless possibilities to construct self-assembled architectures for various applications without time-consuming synthesis. 18 Indeed, nature relies to a large extent on such noncovalent interactions to perform a variety of sophisticated biological functions. The best-known examples include protein

Geometric (Z)- and (E)-isomers play important but different roles in life and material science. The design of new (Z)-/(E)- isomers and study of their properties, behaviors, and interactions are crucially important in molecular engineering. However, difficulties with their separation and structure confirmation limit their structural diversity and functionality in scope. In the work described herein, we successfully synthesized pure isomers of ureidopyrimidinone-functionalized tetraphenylethenes ((Z)-TPE-UPy and (E)-TPE-UPy), featuring both the aggregation-induced emission characteristic of tetraphenylethene and the supramolecular polymerizability of ureidopyrimidinone. Their structures were confirmed by 2D COSY and NOESY NMR spectroscopies. The two isomers show distinct fluorescence in the aggregate state: (Z)-TPE-UPy exhibits green emission, while its (E)-counterpart is blue-emitting. The cavity formed by the two ureidopyrimidinone groups of (Z)-TPE-UPy makes it suitable for Hg detection, and the high-molecular-weight polymers prepared from (E)-TPE-UPy can be used to fabricate highly fluorescent fibers and 2D/3D photopatterns from their chloroform solutions.

A good harvest: Two self‐assembling strategies (micellization and electrostatic attraction) and covalent capture were employed to construct a robust, inexpensive, efficient artificial light‐harvesting system (see picture). The synthesis was achieved by a one‐pot reaction. A high density of the antenna chromophores was achieved without self‐quenching and excimer formation, thus affording extremely efficient energy transfer.

Water-dispersible nanospheres of hydrogen-bonded supramolecular polymers have been prepared for the first time by using the miniemulsion method. Nanospheres containing chromophores with high fluorescence quantum yields were fabricated to mimic the natural light-harvesting system.

5483wileyonlinelibrary.com biocompatibility. Accordingly, there has been a surge in the exploitation of CPNs in numerous exciting studies. [ 9 ] Covalent polymers, however, suffer from the need for tedious chemical modifi cation to tune the emission color of their corresponding nanoparticles.Supramolecular polymers, which are formed from low-molecular-weight monomers by noncovalent interactions, provide a promising scaffold for the fabrication of fl uorescent nanoparticles with well fi ne-tuned emission properties. [ 10 ] On the one hand, the small building blocks of supramolecular polymers provide synthetic accessibility superior to that of covalent polymers. On the other hand, the excitation energy transfer from energy donor to acceptor fl uorophores of the monomers occurs effi ciently in supramolecular copolymers. Such a process can be used to adjust the emission properties of functional materials. [ 11 ] Recently, we have reported the synthesis of water-dispersible nanospheres of hydrogen-bonded supramolecular polymers by the miniemulsion method. [ 12 ] Bis-ureidopyrimidinone (Bis-UPy) monomers polymerized through the quadruple H-bonding of the ureidopyrimidinone (UPy) motif to form supramolecular polymers, [ 13 ] which further aggregated into nanospheres in the emulsifi ed organic droplets. Herein, we prepared FNPs based on fl uorophore-functionalized Bis-UPys by the miniemulsion method ( Scheme 1 ). The emission properties of the nanoparticles could be fi ne-tuned by effi cient excitation energy transfer in co-assemblies of the energy donor and acceptor fl uorophore-based monomers. The photoswitchable FNPs with high on-off fl uorescence contrast (85%) were prepared by copolymerization of Bis-UPys containing fl uorophore and photochromic dithienylethene. The FNPs have been successfully applied in cellular imaging and as fl uorescent inks. Results and Discussion Synthesis, Preparation, and Characterization of FNPsFour fl uorophore-functionalized Bis-UPys were synthesized for the preparation of supramolecular polymer-based fl uorescent nanoparticles: Based on their different emission colors, fl uorophore 9,10-diphenylanthracene, 1,3,5,7-tetramethyl boron dipyrromethene (BODIPY), 3,5-dithiolated BODIPY, and naphthalene bisimide were chosen as the functional groups A facile approach for the preparation of supramolecular polymer-based fl uorescent nanoparticles (FNPs) is reported. FNPs with homogeneous shape and size distribution are fabricated from low-molecular-weight molecules, and thus, different compositional constituents can be effi ciently incorporated via copolymerization. The emission color of the FNPs covers a wide region from blue to near infrared and can be easily tuned using effi cient excitation energy transfer. The photoswitchable fl uorescent nanoparticles with high on-off fl uorescence contrast are also simply prepared by copolymerization of monomers containing a fl uorophore and a photochromic unit. Our FNPs are successfully applied in living cell imaging and as fl uorescent inks.

Artificial light-harvesting nanoparticles were prepared from supramolecular polymers comprised of pillar[5]arene with anthracene-derived donors and acceptors through host-guest interactions. The resulting water-dispersible nanoparticles displayed efficient energy transfer and excellent light harvesting ability in part because the steric bulk of pillar[5]arene suppressed the self-quenching of the chromophores.

Synthetic polymerization and supramolecular polymerization with sequence control are far from an easy task. Herein, a narcissistic self-sorting supramolecular polymer is prepared with a sequence of (−AA−BB−) n by using cucurbit[8]uril (CB[8])-based ternary complexes as supramolecular monomers, which are spontaneously formed from heteroditopic AB-type guest and CB [8]. Supramolecular polymerization and the structural changes at each stage of polymerization have been successfully demonstrated by NMR, UV−vis, and fluorescence spectra. The self-sorting starts from the second step of polymerization after the formation of different ternary complexes as supra-monomers. The dynamic supramolecular interactions and the thermodynamic stability of the host− guest complexes are found to be the crucial factors to drive the sequence control of the supramolecular polymers. Furthermore, the water-soluble supramolecular polymer is red-emissive and can serve as a fluorescent sensor to detect morphine in artificial urine with considerable stability, sensitivity, and accuracy. And it can also distinguish heroin and morphine, two kinds of opioids with similar structures.

5419wileyonlinelibrary.com signifi cant efforts have been devoted toward developing optical sensors for oxygen. [6][7][8][9][10][11] Quenching of phosphorescence is a powerful tool for oxygen sensing due to its invasiveness, selectivity, and (when applied in specifi c systems) sensitivity to oxygen. In addition, it can measure and map oxygen with high-resolution and in real-time in cells and tissues. Ratiometric oxygen sensing at two wavelengths allows for better calibration of oxygen levels and is more desirable in the chemical and medical fi elds than simple phosphorescence quenching. In a ratiometric sensor, oxygen concentration is calculated from the phosphorescence of an indicator dye and the fl uorescence of a reference dye. In the literature, such ratiometric oxygen sensors have been constructed by incorporation of phosphorescent dyes such as Pd(II)/Pt(II) porphyrin complexes inside conjugated polymer nanoparticles, [ 8 ] quantum dots, [ 9 ] silica gels, [ 10 ] and metal-organic frameworks. [ 11 ] Supramolecular polymers (SP), which are prepared from low-molecular-weight monomeric units that are associated through reversible noncovalent interactions (and thus different compositional constituents) can be effi ciently incorporated by copolymerization and provide a promising scaffold to fabricate phosphorescent functional nanomaterial for oxygen sensing. [ 12,13 ] In contrast to the rapid development of conjugated polymer nanoparticles for biosensing and bioimaging applications, [ 8 ] nanomaterials constructed from supramolecular polymers for sensing are still rare. [ 14 ] This can be attributed to the small number of examples of supramolecular polymers that have been found to form uniform nanostructures in water and are compatible with biological systems. Recently, we reported the construction of water-dispersible nanoparticles based on ureidopyrimidinone (UPy) quadruple hydrogen-bonded supramolecular polymers by a mini-emulsion method. [ 15 ] These nanoparticles exhibit several characteristics that make them ideal candidate for biological and biomedical applications. First, they have good structural and functional tunability because they are constructed from low-molecular-weight molecules, allowing synthetic elaborations for specifi c applications. Second, the nanoparticles are dispersed uniformly in aqueous solutions and stable for reasonably long periods. Third, the sizes of the nanoparticles are controllable by the concentration and type of the skeleton units. The small sizes of the nanoparticles should produce minimal cell damage and allow better cellular uptakeThe fi rst example of a ratiometric optical oxygen nanoprobe based on a hydrogen-bonded supramolecular polymer has been reported. The supramolecular polymer based nanoprobe (SPNP) is prepared from the co-assembly of a bis-ureidopyrimidinone (bis-UPy)-containing phosphorescent indicator (Por(Pd)-bisUPy), fl uorescent reference dye (BF 2 -bisUPy), and skeleton unit (DPA-bisUPy) through quadruple hydrogen bonds by a mini-emulsion method. The water-...