Smart organic materials based on macrocycle hosts

Innovative design of smart organic materials is of great importance for the advancement of modern technology. Macrocycle hosts, possessing cyclic skeletons, intrinsic cavities, and specific guest binding properties, have demonstrated pronounced potential for the elaborate fabrication of a variety of functional organic materials with smart stimuli-responsive characteristics. In this tutorial review, we outline the current development of smart organic materials based on macrocycle hosts as key building blocks, focusing on the design principles and functional mechanisms of the tailored systems. Three main types of macrocycle-based smart organic materials are exemplified as follows according to the distinct forms of construction patterns: (1) supramolecular polymeric materials and nanoassemblies; (2) adaptive molecular crystals; (3) smart porous organic materials. The responsive performances of macrocycle-containing smart materials in versatile aspects, including mechanically adaptive polymers, soft optoelectronic devices, data encryption, drug delivery systems, artificial transmembrane channels, crystalline-state gas adsorption/separation, and fluorescence sensing, are illustrated by discussing the representative studies as paradigms, where the roles of macrocycles in these systems are highlighted. We also provide in the conclusion part the perspectives and remaining challenges in this burgeoning field.

The Creation of DNA Origami-Based Supramolecular Nanostructures for Cancer Therapy

DNA origami technology, a unique type of DNA nanotechnology, has attracted much attention from researchers and is applied in various fields. Through exquisite design and precise self-assembly of four kinds of deoxyribonucleotides, DNA origami nanostructures are endowed with excellent programmability and addressability and show outstanding biocompatibility in bio-related applications, especially in cancer treatment. In this review, nanomaterials based on DNA origami for cancer therapy are concluded, whereby chemotherapy and photo-assisted therapy are the main focus. Furthermore, the working mechanisms of the functional materials attached to the rigid DNA structures to enable targeted delivery and circumvent drug resistance are also discussed. DNA origami nanostructures are valuable carriers for delivering multifunctional therapeutic agents and demonstrate great potential in cancer treatment both in vitro and in vivo. It is undoubted that DNA origami technology is a promising strategy for constructing versatile nanodevices in biological fields and will excel in human healthcare.

Aggregation-Induced Emission (AIE), Life and Health

Light has profoundly impacted modern medicine and healthcare, with numerous luminescent agents and imaging techniques currently being used to assess health and treat diseases. As an emerging concept in luminescence, aggregation-induced emission (AIE) has shown great potential in biological applications due to its advantages in terms of brightness, biocompatibility, photostability, and positive correlation with concentration. This review provides a comprehensive summary of AIE luminogens applied in imaging of biological structure and dynamic physiological processes, disease diagnosis and treatment, and detection and monitoring of specific analytes, followed by representative works. Discussions on critical issues and perspectives on future directions are also included. This review aims to stimulate the interest of researchers from different fields, including chemistry, biology, materials science, medicine, etc., thus promoting the development of AIE in the fields of life and health.

Macrocycle-Strutted Coordination Microparticles for Fluorescence-Monitored Photosensitization and Substrate-Selective Photocatalytic Degradation

The prosperous advancement of supramolecular chemistry has motivated us to construct supramolecular hybrid materials with integrated functionalities. Herein, we report an innovative type of macrocycle-strutted coordination microparticle (MSCM) using pillararenes as the struts and "pockets", which performs unique activities of fluorescence-monitored photosensitization and substrate-selective photocatalytic degradation. Prepared via a convenient one-step solvothermal method, MSCM showcases the incorporation of supramolecular hybridization and macrocycles, endowed with well-ordered spherical architectures, superior photophysical properties, and photosensitizing capacity, where a self-reporting fluorescence response is exhibited upon photoinduced generation of multiple reactive oxygen species. Importantly, photocatalytic behaviors of MSCM show marked divergence toward three different substrates and reveal pronounced substrate-selective catalytic mechanisms, attributing to the variety in the affinity of substrates toward MSCM surfaces and pillararene cavities. This study brings new insight into the design of supramolecular hybrid systems with integrated properties and further exploration of functional macrocycle-based materials.

Tunable Photochromism of Spirooxazine in the Solid State: A New Design Strategy Based on the Hypochromic Effect

As an important organic photofunctional material, spirooxazine (SO) usually does not exhibit photochromism in the solid state since the intermolecular π-π stacking impedes photoisomerization. Developing photochromic SO in the solid state is crucial for practical applications but is still full of challenges. Here, a series of spirooxazine derivatives (SO1-SO4) with bulky aromatic substituents at the 4- and 7-positions of the skeleton, which provide them with a large volume with which to undergo solid-state photochromism under mild conditions, is designed and synthesized. All the compounds SO1-SO4 exhibit tunable solid photochromism without ground colors, excellent fatigue resistance, and high thermal stability. Notably, it takes only 15 s for SO4 to reach the saturation of absorption intensity, thought to represent the fastest solid-state photoresponse of spirooxazines. X-ray crystal structures of the intermediate compound SO0 and the products SO1-SO2 as well as computational studies suggest that the bulky aromatic groups can lead to a hypochromic effect, allowing for the photochromism of SO in the solid state. The ideal photochromic properties of these spirooxazines open a new avenue for their applications in UV printing, quick response code, and related fields.

Pillararene-based molecular-scale porous materials

This review discusses the design and syntheses of molecular-scale pillar[n]arene-based porous materials with promising applications and summarises the development of using pillar[n]arenes as the building blocks of porous materials. From the perspective of "role of participation" in the syntheses of molecular-scale pillar[n]arene-based porous materials, the content can be divided into pillar[n]arenes serving as supramolecular nanovalves on surfaces and as ligands for metal-organic frameworks and covalent organic polymers. By integrating pillararenes, which possess rigid pillar-like structures, electron-rich cavities and desirable host-guest properties, with porous polymers of large surface areas and abundant active sites, applications of the resulting materials in drug release platforms, molecular recognition, sensing, detection, gas adsorption, removal of water pollution, organic photovoltaic materials and heterogeneous catalysis can be realised simultaneously and efficiently. Finally, in the conclusions and perspectives part, we put forward the challenges and viewpoints of the current research on pillar[n]arene-based porous materials. We hope this article can provide a timely and valuable reference for researchers interested in synthetic macrocycles and porous materials.

Polyacrylamide-Based Binary Luminescent Copolymer Materials Exhibit Color-Tunable and Efficient Long-Lived Room Temperature Phosphorescence

Polymer-based pure organic room temperature phosphorescence (RTP) materials have garnered considerable interest, among which RTP systems with prolonged lifetimes and tunable emission colors are promising for applications in sensing, flexible electronics, bioassay, anti-counterfeiting, and data encryption. Herein, facile doping method is reported based on two types of copolymers with benzene/biphenyl-based light-emitting cores as their side chains, whereby the two copolymers are robustly crosslinked via noncovalent interactions including hydrogen bonding and halogen bonding that occur between the light-emitting cores and polyacrylamide backbones. Persistent RTP emission with prolonged lifetime up to 1.9 s and phosphorescence quantum yield as high as 40.1% are obtained in single copolymers, attributed to the conformation restriction of phosphorescent dyes originating from the rigid microenvironment. Furthermore, multicolor phosphorescence signals are observed in the doped binary luminescent copolymer systems that can be effectively regulated by the feed ratio of luminescent cores and irradiation wavelengths. Possible mechanisms for this efficient and long-lived color-tunable RTP system are discussed on the basis of the experimental data and theoretical calculations. In addition, it is also demonstrated that the color-tunable RTP emission of the doped copolymer systems under ambient conditions allows for further exploitation in the application of dynamic information encryption.

Pyridine-Conjugated Pillar[5]arene: From Molecular Crystals of Blue Luminescence to Red-Emissive Coordination Nanocrystals

A luminescent molecular crystal (P5bipy) and a Cu(I)-coordinated luminescent nanocrystal (Cu(I)-P5bipy) have been prepared concurrently using one conjugated pillar[5]arene macrocycle via a facile supramolecular self-assembling strategy. The molecular crystal shows enhanced luminescence compared with unmodified pillar[5]arene, attributed to its conjugated structure and staggered packing mode, while the coordination nanocrystal exhibits well-defined crystalline structures and long-lifetime triplet state emission along with pronounced solvochromic features.

Supramolecular Nanoplatform Based on Mesoporous Silica Nanocarriers and Pillararene Nanogates for Fungus Control

Synthetic fungicides have been widely used to protect crops from fungal diseases. However, excessive use of synthetic fungicides leads to the generation of fungicide resistance in fungal pathogens. Recently, smart cargo delivery systems have been introduced for the construction of a pesticide delivery nanoplatform, benefiting from their controlled release performance. Herein, a fungal pathogen microenvironment-responsive supramolecular fungicide nanoplatform has been designed and constructed, using quaternary ammonium salt (Q)-modified mesoporous silica nanoparticles (MSN-Q NPs) as nanocarriers loaded with berberine hydrochloride (BH) and carboxylatopillar[5]arene (CP[5]A) as nanogates to form BH-loaded CP[5]A@MSN-Q NPs for effective inhibition of Botrytis cinerea. CP[5]A as nanogates can endow the fungicide nanoplatform with pH stimuli-responsive release features for the control of fungicide release. The loaded BH, as a natural plant fungicide, provides an ecofriendly alternative to synthetic fungicides for controlling B. cinerea. Interestingly, we use oxalic acid (OA) secreted by B. cinerea as a trigger so that BH can be released from the fungicide nanoplatform on demand under pathogen microenvironments for controlling B. cinerea. The experimental results indicate that the fabricated fungicide nanoplatform could effectively inhibit the mycelial growth and spore germination, providing a new way for the management of B. cinerea in actual application.

A stimuli-responsive pillar[5]arene-based hybrid material with enhanced tunable multicolor luminescence and ion-sensing ability

Tunable luminescent materials are becoming more and more important owing to their broad application potential in various fields. Here we construct a pillar[5]arene-based hybrid material with stimuli-responsive luminescent properties and ion-sensing abilities from a pyridine-modified conjugated pillar[5]arene and a planar chromophore oligo(phenylenevinylene) upon coordination of Cd (II) metal cores. This new material not only shows an optimized luminescence due to the minimized π-π stacking and efficient charge transfer properties benefitting from the existence of pillar[5]arene rings, but also exhibits tunable multicolor emission induced by different external stimuli including solvent, ions and acid, indicating great application potential as a fluorescent sensory material, especially for Fe3+. With this pillar[5]arene-based dual-ligand hybrid material, valid optimization and regulation on the fluorescence of the original chromophore have been achieved, which demonstrates a plausible strategy for the design of tunable solid-state luminescent materials and also a prototypical model for the effective regulation of fluorescent properties of planar π systems using synthetic macrocycle-based building blocks.

Supramolecular Engineering of Efficient Artificial Light-Harvesting Systems from Cyanovinylene Chromophores and Pillar[5]arene-Based Polymer Hosts

Enhanced emission and adjustable wavelength for single luminogen systems are highly desirable in the scope of photoluminescent materials. Herein, a supramolecular strategy has been proposed for supramolecular assembly-induced enhanced emission and valid emission manipulation by fabricating an amphiphilic copolymer host material with pillar[5]arene units as the side chains, whereby cyanovinylene-based (CV) derivatives are anchored to the polymer hosts via host-guest interactions. The guest-bearing copolymers can further form luminescent supramolecular polymer nanoparticles (SPNs). Remarkably, the as-prepared SPNs exhibit dramatic emission enhancement and tunable fluorescence wavelength, ascribing to the synergetic effects involving the restriction of intramolecular motions and the prevented excimer formation for CV moieties, as endowed by host-guest interactions and the entanglement of the polymer chains. Furthermore, the SPNs can be established as efficient artificial light-harvesting systems via the inclusion of Nile red into the particles for broadened emission spectra. As a proof-of-concept study, the use of pillar[5]arene-containing polymer hosts largely facilitates the emission enhancement and wavelength adjustment for the inherent luminogens, setting the basis for the supramolecular design of highly tunable luminescent systems.

Pillar[n]arene-Based Supramolecular Switches in Solution and on Surfaces

The design and synthesis of new synthetic macrocycles has driven the rapid development of supramolecular chemistry and materials. Pillar[n]arenes, as a new type of macrocyclic compounds, are used as a promising type of building blocks for switchable supramolecular systems due to their versatile functionalization and the ability of binding toward various guest molecules. A number of guests can form inclusion complexes with pillar[n]arenes and their derivatives in solution, which are sensitive to different external triggers. Interestingly, the pursuit of complex stimuli-responsive functional materials and devices has largely motivated the shift of pillar[n]arene-based switches from solution media to surfaces for controllable macroscopic motions on solid platforms. Facilitated by the facile modification of pillar[n]arenes on various solid supports and the dynamic binding of host-guest complexes, numerous functional hybrid materials with adjustable physical or chemical properties and integrated functionalities have been reported in the last decade. Here, the advance of supramolecular switches in solution and on surfaces based on pillar[n]arenes and derivatives with an emphasis on the efforts and the latest contributions from the field is discussed.

A Binary Supramolecular Assembly with Intense Fluorescence Emission, High pH Stability, and Cation Selectivity: Supramolecular Assembly-Induced Emission Materials

We construct a fluorescent supramolecular system (TPE-Q₄ ⊂ DSP5) of excellent tolerance to a wide range of pH by the facile self-assembly of a new pillar[5]arene bearing disulfonated arms (DSP5) with an AIE-active tetraphenylethene-based tetratopic guest bearing four quaternary ammonium binding sites (TPE-Q₄), which exhibits strong blue emission even in dilute aqueous solutions along with much higher quantum yield and longer fluorescence lifetime than TPE-Q₄ itself. This appreciable property can be attributed to the supramolecular assembly-induced emission (SAIE) mechanism endowed by the host-guest inclusion complexation based on synthetic macrocycles. Remarkably, the enhanced fluorescence of the supramolecular assembly is quenched efficiently and exclusively by ferric ions in water with a high Stern-Volmer formula constant of 1.3 × 10⁵  mol^-1, demonstrating the excellent cation selectivity and visualized responsiveness in ion sensing and detection.

Supramolecular nanotheranostics based on pillarenes

With the rapid development of supramolecular chemistry and nanomaterials, supramolecular nanotheranostics has attracted remarkable attention owing to the advantages compared with conventional medicine. Supramolecular architectures relying on non-covalent interactions possess reversible and stimuli-responsive features; endowing supramolecular nanotheranostics based on supramolecular assemblies great potentials for the fabrication of integrated novel nanomedicines and controlled drug delivery systems. In particular, pillarenes, as a relatively new class of synthetic macrocycles, are important candidates in the construction of supramolecular therapeutic systems due to their excellent features such as rigid and symmetric structures, facile substitution, and unique host-guest properties. This review summarizes the development of pillarene-based supramolecular nanotheranostics for applications in biological mimicking, virus inhibition, cancer therapy, and diagnosis, which contains the following two major parts: (a) pillarene-based hybrid supramolecular nanotheranostics upon hybridizing with porous materials such as mesoporous silica nanoparticles, metal-organic frameworks, metal nanoparticles, and other inorganic materials; (b) pillarene-based organic supramolecular therapeutic systems that include supramolecular amphiphilic systems, artificial channels, and prodrugs based on host-guest complexes. Finally, perspectives on how pillarene-based supramolecular nanotheranostics will advance the field of pharmaceuticals and therapeutics are given.

Gated Materials: Installing Macrocyclic Arenes-Based Supramolecular Nanovalves on Porous Nanomaterials for Controlled Cargo Release

Supramolecular nanovalves are an emerging class of important elements that are functionalized on the surfaces of inorganic or hybrid nanocarriers in the constructions of smart cargo delivery systems. Taking advantage of the pseudorotaxane structure via host-guest complexation and the dynamic nature of supramolecular interactions, macrocyclic arene-based supramolecular nanovalves have shown great promise in the applications of drug delivery and controlled release. Careful selection of diverse external stimuli, such as pH variations, temperature changes, redox, enzymes, light irradiation, and competitive binding, can activate the opening and closing of the nanovalves by altering the supramolecular structure or binding affinities. Meanwhile, the porous solid supports in controlled release systems also play an important role in the functionalities of the nanocarriers, which include, but not limited to, mesoporous silica nanoparticles (MSNs), metal-organic frameworks (MOFs), core-shell nanomaterials, and rare-earth porous nanomaterials. The elaborate decoration by macrocyclic arenes-based supramolecular nanovalves on porous nanomaterials has provided intelligent controlled release platforms. In this review, we will focus on the overview of supramolecular nanovalves based on two typical macrocyclic arenes, that is, calixarenes and pillarenes, and their operation manners in the controlled release processes.

Fluorescence Resonance Energy Transfer Systems in Supramolecular Macrocyclic Chemistry

The fabrication of smart materials is gradually becoming a research focus in nanotechnology and materials science. An important criterion of smart materials is the capacity of stimuli-responsiveness, while another lies in selective recognition. Accordingly, supramolecular host-guest chemistry has proven a promising support for building intelligent, responsive systems; hence, synthetic macrocyclic hosts, such as calixarenes, cucurbiturils, cyclodextrins, and pillararenes, have been used as ideal building blocks. Meanwhile, manipulating and harnessing light artificially is always an intensive attempt for scientists in order to meet the urgent demands of technological developments. Fluorescence resonance energy transfer (FRET), known as a well-studied luminescent activity and also a powerful tool in spectroscopic area, has been investigated from various facets, of which the application range has been broadly expanded. In this review, the innovative collaboration between FRET and supramolecular macrocyclic chemistry will be presented and depicted with typical examples. Facilitated by the dynamic features of supramolecular macrocyclic motifs, a large variety of FRET systems have been designed and organized, resulting in promising optical materials with potential for applications in protein assembly, enzyme assays, diagnosis, drug delivery monitoring, sensing, photosynthesis mimicking and chemical encryption.

The QTL analysis on maternal and endosperm genome and their environmental interactions for characters of cooking quality in rice (Oryza sativa L.)

Investigations to identify quantitative trait loci (QTLs) governing cooking quality traits including amylose content, gel consistency and gelatinization temperature (expressed by the alkali spread value) were conducted using a set of 241 RIL populations derived from an elite hybrid cross of "Zhenshan 97"x"Minghui 63" and their reciprocal backcrosses BC1F1 and BC2F1 populations in two environments. QTLs and QTLxenvironment interactions were analyzed by using the genetic model with endosperm and maternal effects and environmental interaction effects on quantitative traits of seed in cereal crops. The results suggested that a total of seven QTLs were associated with cooking quality of rice, which were subsequently mapped to chromosomes 1, 4 and 6. Six of these QTLs were also found to have environmental interaction effects.

Reserved Sertoli cell function in the hypogonadic male patients with myotonic dystrophy

To clarify the Sertoli cell and Leydig cell function in hypogonadic male patients with myotonic dystrophy (DM), serum concentrations of inhibin, total testosterone (TT), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were measured by radioimmunoassay in 6 male DM patients (41 to 56 years old, 47.7 +/- 5.05 years old) and compared with those in normal adult men. In 116 healthy men aged from 24 to 92 years, serum inhibin and TT levels decreased and serum FSH and LH concentrations increased with advancing age. There was an inverse correlation between serum inhibin and FSH. These results support the concept of negative feedback regulation system of FSH secretion by inhibin. Male DM patients showed significantly lower serum TT and higher concentrations of FSH and LH, compared with the age-matched 39 normal adult men (49-59 years old, 48.2 +/- 6.14 years old). However, there was no significant difference in serum inhibin levels between the patients and normal counterparts. These results indicate that the Sertoli cell function is reserved in male DM patient, although the Leydig cell function is impaired. It is also suggested that in these patients a negative feedback control system between inhibin and FSH may be disordered to some extent.