The single crystal of M-4-B was obtained by attaching the boron of BH₃ to the amine linker between a tetraphenylethylene (TPE) unit and rhodamine B. M-4-B showed a novel sequential tricolor switching from dark blue to bluish-green and to a reddish color upon grinding. The boron atom played a key role in developing the single crystal.

The single crystal of M-4-B was obtained by attaching the boron of BH₃ to the amine linker between a tetraphenylethylene (TPE) unit and rhodamine B. M-4-B showed a novel sequential tricolor switching from dark blue to bluish-green and to a reddish color upon grinding. The boron atom played a key role in developing the single crystal.

Mechanofluorochromic or piezochromic fluorescence chemistry involves the switching and tuning of the luminescent properties of solid-state materials induced by exogenous forces, such as grinding, shearing, compression, tension, and so forth. Up until now, most reported mechanochromic systems, including liquid crystals, organic molecules, organometallic compounds, polymers, and dye-doped polymers, have displayed reversible two-color changes, which arise from either supramolecular or chemical structure transformations. However, fluorescent materials that undergo mechanically induced multicolor changes remain rare; this Minireview is focused on such materials. Topics are categorized according to the different applied forces that are required to induce the multicolor change, including mechanical control of either the supramolecular structures or the chemical structures, and mechanical control of both the supramolecular structures and chemical structures.

The azomethine-based oligomers bearing boronate groups and imine moieties in the main chain were synthesized from a dialdehyde monomer and an aromatic (oligomer 4) diamine or an aliphatic diamine (oligomer 5). Based on the oligomers, the nanoparticles with hydrogen peroxide (H₂O₂) and pH dual-responsive properties were constructed and encapsulated nile red inside. The nanoparticles disassembled either by the trigger of H₂O₂ or by the attack of H⁺, thus leading to the release of loaded species. Compared to oligomer 4, oligomer 5 showed a faster degradation rate in the presence of H₂O₂, especially in a weak acidic environment. No significant cytotoxicity was observed as HeLa cells incubated in the nanoparticles with the concentration up to 200 μg/mL evidenced by cytotoxicity assay in vitro. Such a system capable of dual response of H₂O₂ and H⁺ may have potential application as a carrier for drug delivery. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1962–1969

As a mimic of protein, a polyampholyte-based material should be able to duplicate the properties and functions of protein. A polyampholyte that is highly sensitive to both pH and temperature under physiological conditions is obtained when 80% butylamide-terminated poly(amidoamine) dentron is grafted to the backbone of styrene and maleic anhydride. The phase separation occurs at 33.7 °C at pH = 6.20, while the transition point increases to 43.9 °C at pH = 6.30. The superior performance is the consequence of the cooperative interactions among basic, acidic, and thermoresponsive groups. The polyampholyte with a suitable isoelectric point provides a platform for the development of multifunctional materials for biomedical applications.

There is a delicate balance for a low-weight molecule to behave as a gelator or crystal. The synthesis of two novel amino acid-based naphthalene-dendrons, Nap-G1 and Nap-G2 is described. Both dendrons display polymorphic properties in organic solvents. Nap-G1 developed a fibrous network with β-sheet architecture in cyclohexane but exhibited a spherulitic network in mixed solvents (chloroform/petroleum ether 1:5, v/v). On the other hand, Nap-G2 acted as an efficient organogelator in chloroform but formed crystalline fibers in relatively high polarity solvents (such as acetone and methanol). Combinations of characterizations have been employed to study the polymorphism.

Gn (n = 3, 4, and 5) poly(amidoamine) (PAMAM) dendrimers were synthesized and peripherally modified with photocleavable o-nitrobenzyl (NB) groups by reacting o-nitrobenzaldehyde with the terminal amine groups of PAMAM dendrimers, followed by reducing the imine to amine groups with NaBH₄. The NB-modified dendrimers, Gn-NB (n = 3, 4, and 5), were characterized by nuclear magnetic resonance and fourier transform infrared spectroscopy. The results showed that the NB groups were successfully attached on the periphery of the dendrimers with near 100% grafting efficiency. Such a photosensitive NB shell could be cut off on irradiation with 365 nm ultraviolet (UV) light. The encapsulation and release of guest molecules, that is, salicylic acid (SA) and adriamycin (ADR), by Gn-NB were explored. The encapsulation capability of these dendrimers was found to increase as the guest molecular size was decreased and have dependence on the generation of dendrimers as well. For both of SA and ADR, the average encapsulation numbers per dendrimer decreased in the order of G4-NB > G5-NB > G3-NB, indicating that the fourth generation dendrimer was a better container for the guest molecules. The rate of SA release was found to be greater with UV irradiation than that without, suggesting that the NB-shelled PAMMAM dendrimers could function as a molecular container/box with photoresponsive characteristics. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 551–557, 2010

Two series of amphiphiles composed of hydrophilic poly(amidoamine) dendrons (from the first to the third generation) as the shell and hydrophobic aromatic chromophores (3,6-di(maleimidyl)-9-phenyl carbazole and 9-(4′-maleimidyl phenyl)-3-maleimidyl carbazole) as the central scaffold were synthesized. The effect of dendritic architecture on the photophysical properties and the self-assembly behavior of these amphiphiles were studied by UV–vis absorption spectroscopy, fluorescence spectroscopy, and transmission electron microscopy (TEM) measurements. Both the generation of dendritic shell and the location of dendrons at the chromophoric scaffold had great effect on the photophysical properties of these amphiphiles. In addition, different spherical aggregates were formed from these amphiphiles in the aqueous solution at different concentrations. Because of the combined effects of steric hindrance and architecture of dendritic shells, the amphiphiles from G2 dendron with central chromophore self-organized into ordered aggregates more readily than that from G1 and G3. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4584–4593, 2008