Modified Breath Figure Methods for the Pore-Selective Functionalization of Honeycomb-Patterned Porous Polymer Films

Recent developments in the field of the breath figure (BF) method have led to renewed interest from researchers in the pore-selective functionalization of honeycomb-patterned (HCP) films. The pore-selective functionalization of the HCP film gives unique properties to the film which can be used for specific applications such as protein recognition, catalysis, selective cell culturing, and drug delivery. There are several comprehensive reviews available for the pore-selective functionalization by the self-assembly process. However, considerable progress in preparation technologies and incorporation of new materials inside the pore surface for exact applications have emerged, thus warranting a review. In this review, we have focused on the pore-selective functionalization of the HCP films by the modified BF method, in which the self-assembly process is accompanied by an interfacial reaction. We review the importance of pore-selective functionalization, its applications, present limitations, and future perspectives.

Molecular Architectonics-guided Design of Biomaterials

The quest for mastering the controlled engineering of dynamic molecular assemblies is the basis of molecular architectonics. The rational use of noncovalent interactions to programme the molecular assemblies allow the construction of diverse molecular and material architectures with novel functional properties and applications. Understanding and controlling the assembly of molecular systems are daunting tasks owing to the complex factors that govern at the molecular level. Molecular architectures depend on the design of functional molecular modules through the judicious selection of functional core and auxiliary units to guide the precise molecular assembly and co-assembly patterns. Biomolecules with built-in information for molecular recognition are the ultimate examples of evolutionary guided molecular recognition systems that define the structure and functions of living organisms. Explicit use of biomolecules as auxiliary units to command the molecular assemblies of functional molecules is an intriguing exercise in the scheme of molecular architectonics. In this minireview, we discuss the implementation of the principles of molecular architectonics for the development of novel biomaterials with functional properties and applications ranging from sensing, drug delivery to neurogeneration and tissue engineering. We present the molecular designs pioneered by our group owing to the requirement and scope of the article while acknowledging the designs pursued by several research groups that befit the concept.

Hierarchical Self-Assembly of Toroidal Micelles into Multidimensional Nanoporous Superstructures

Materials with controlled porosity play a prominent role in industrial and domestic applications. Although a rich array of methods has been developed to tune the pore size over a broad range (from <1 nm to >1 μm), the fabrication of functional materials with a fully open porous structure with sub-100 nm pore size has remained a significant challenge. Herein, we report the hierarchical assembly of block copolymer toroidal micelles with an intrinsic cavity into multidimensional nanoporous superstructures (pore size 85-90 nm) by modulation of interparticle interactions. The toroids aggregate into oligo-supermicelles or 2D hexagonal arrays through van der Waals interactions upon drying on a substrate, while synergistic hydrogen bonding interactions further promote the formation of 3D nanoporous superstructures directly in solution. Thus, toroidal micelles can be manipulated as a type of distinctive building block to construct nanoporous materials.

Facile access to deep red/near-infrared emissive AIEgens for efficient non-doped OLEDs

Notwithstanding the huge demand in bio-imaging and optoelectronics, the construction of highly emissive deep red/near infrared (DR/NIR) organic luminogens is still a big challenge because a narrow energy gap generally leads to low photoluminescence quantum yield. It is even more difficult to afford DR/NIR emitters in the solid state due to the aggregation caused quenching (ACQ) effect. In this work, we found that the direct attachment of a tetraphenylethylene substituted arylamine to the electron accepting 2,1,3-benzothiadiazole produces DR/NIR AIE luminogens with bright emission facilely and efficiently. And the emission wavelengths could be tuned from the red to the DR/NIR region by regulating the variety of the substituents. The long emission wavelength and high photoluminescence quantum yield of these AIEgens are ascribed to the effective intramolecular charge transfer and the suppressed intramolecular motion. Furthermore, non-doped OLEDs based on one of the AIEgens showed an EL emission at 684 nm with a large radiance of 5772 mW Sr-1 m-2 and an impressive external quantum efficiency (EQE) of 1.73%.

Architectonics: Design of Molecular Architecture for Functional Applications

The term architectonics has its roots in the architectural and philosophical (as early as 1600s) literature that refers to "the theory of structure" and "the structure of theory", respectively. The concept of architectonics has been adapted to advance the field of molecular self-assembly and termed as molecular architectonics. In essence, the methodology of organizing molecular units in the required and controlled configurations to develop advanced functional systems for materials and biological applications comprises the field of molecular architectonics. This concept of designing noncovalent systems enables to focus on different functional aspects of designer molecules for biological and nonbiological applications and also strengthens our efforts toward the mastery over the art of controlled molecular self-assemblies. Programming complex molecular interactions and assemblies for specific functions has been one of the most challenging tasks in the modern era. Meticulously ordered molecular assemblies can impart remarkable developments in several areas spanning energy, health, and environment. For example, the well-defined nano-, micro-, and macroarchitectures of functional molecules with specific molecular ordering possess potential applications in flexible electronics, photovoltaics, photonic crystals, microreactors, sensors, drug delivery, biomedicine, and superhydrophobic coatings, among others. The functional molecular architectures having unparalleled properties are widely evident in various designs of Nature. By drawing inspirations from Nature, intended molecular architectures can be designed and developed to harvest various functions, as there is an inexhaustible resource and scope. In this Account, we present exquisite designer molecules developed by our group and others with an objective to master the art of molecular recognition and self-assembly for functional applications. We demonstrate the tailor-ability of molecular self-assemblies by employing biomolecules like amino acids and nucleobases as auxiliaries. Naphthalenediimide (NDI), perylenediimide (PDI), and few other molecular systems serve as functional modules. The effects of stereochemistry and minute structural modifications in the molecular designs on the supramolecular interactions, and construction of self-assembled zero-dimensional (OD), one-dimensional (1D), and two-dimensional (2D) nano- and microarchitectures like particles, spheres, cups, bowls, fibers, belts, helical belts, supercoiled helices, sheets, fractals, and honeycomb-like arrays are discussed in extensive detail. Additionally, we present molecular systems that showcase the elegant designs of coassembly, templated assembly, hierarchical assembly, transient self-assembly, chiral denaturation, retentive helical memory, self-replication, supramolecular regulation, supramolecular speciation, supernon linearity, dynamic pathway complexity, supramolecular heterojunction, living supramolecular polymerization, and molecular machines. Finally, we describe the molecular engineering principles learnt over the years that have led to several applications, namely, organic electronics, self-cleaning, high-mechanical strength, and tissue engineering.

Honeycomb-patterned hybrid films of surfactant-encapsulated polyoxometalates by a breath figure method and its electrocatalysis for BrO3−

Surfactant-encapsulated POMs can self-assemble into ordered porous honeycomb films under a moist atmosphere. We successfully fabricated (DODA)₁₀{Cu₄(PW₉)₂} honeycomb films by using a one-step method.

Wettability with Aggregation-Induced Emission Luminogens

Aggregation-induced emission luminogens (AIEgens) have become an emerging field since the concept of AIE was proposed in 2001. Recently, AIEgens have attracted considerable attention due to their abnormal non-emissive fluorescent behavior in solution but strongly emissive behavior in the aggregate state. By utilizing the inherent hydrophobicity, AIEgens can be used to monitor the crystal formation and dewetting behavior in the self-assembly process. More importantly, some stimuli-responsive AIE-active surfaces have been successfully fabricated. In this perspective review, we outline the advances of surface wettability of AIEgens and its applications.

A new AIE multi-block polyurethane copolymer material for subcellular microfilament imaging in living cells

A multi-block fluorescent amphiphilic polyurethane copolymer (TPE-PU), self-assembling into hairy, water-soluble micelles, is used as a subcellular microfilament probe in living cells.

Conformal and non-conformal surface modification of honeycomb-patterned porous films via tunable Cassie–Wenzel transition

We describe here a facile and robust approach to conformal and non-conformal surface modification by tuning the wetting transition between the Wenzel state and the Cassie state.

Phosphorescent organoplatinum(II) complexes with a lipophilic anion: supramolecular soft nanomaterials through ionic self-assembly and metallophilicity

Upon switching the counter-ion to a highly lipophilic anion, a series of phosphorescent cationic organoplatinum(II) salts are rendered soluble in non-polar solvents and can further self-organize into lamellar nanostructures, breath-figure arrays and smectic mesophases.

Single-step fabrication of large-scale patterned honeycomb structures via self-assembly of a small organic molecule

A schematic diagram of honeycomb structure formation from AOB-t8.

An aggregation-induced-emission platform for direct visualization of interfacial dynamic self-assembly

An in-depth understanding of dynamic interfacial self-assembly processes is essential for a wide range of topics in theoretical physics, materials design, and biomedical research. However, direct monitoring of such processes is hampered by the poor imaging contrast of a thin interfacial layer. We report in situ imaging technology capable of selectively highlighting self-assembly at the phase boundary in real time by employing the unique photophysical properties of aggregation-induced emission. Its application to the study of breath-figure formation, an immensely useful yet poorly understood phenomenon, provided a mechanistic model supported by direct visualization of all main steps and fully corroborated by simulation and theoretical analysis. This platform is expected to advance the understanding of the dynamic phase-transition phenomena, offer insights into interfacial biological processes, and guide development of novel self-assembly technologies.

Synthesis of core cross-linked star polystyrene with functional end groups and self-assemblies templated by breath figures

We report the synthesis of core cross-linked star (CCS) polymers with functional end groups for self-assembled films, which show mono-layer and multi-layer transition, depending on arm numbers, arm length, and end groups.

Multiple interfaces in self-assembled breath figures

Progress in the breath figure method is reviewed by emphasizing the role of the multiple interfaces and the applications of honeycomb films in separation, biocatalysis, biosensing, templating, stimuli-responsive surfaces and adhesive surfaces.

Probing the dendritic architecture through AIE: challenges and successes

Since the aggregation-induced emission (AIE) phenomenon is very sensitive to steric hindrance, we set out to use it as a tool to probe the periphery of dendrimers.

Ordered honeycomb structural interfaces for anticancer cells growth

The patterned honeycomb structure film with the aggregation-induced emission property was prepared successfully by the breath figure method and photopolymerization method. Characterization of the HeLa and HepG2 cell culture on this surface indicates the porous honeycomb structures show anticancer cells growth function. So this kind of honeycomb structure will be promising for the control of cancer cell growth behaviors and achieving the application of anticancer.

Advances in Fabrication Materials of Honeycomb Structure Films by the Breath-Figure Method

Creatures in nature possess almost perfect structures and properties, and exhibit harmonization and unification between structure and function. Biomimetics, mimicking nature for engineering solutions, provides a model for the development of functional surfaces with special properties. Recently, honeycomb structure materials have attracted wide attention for both fundamental research and practical applications and have become an increasingly hot research topic. Though progress in the field of breath-figure formation has been reviewed, the advance in the fabrication materials of bio-inspired honeycomb structure films has not been discussed. Here we review the recent progress of honeycomb structure fabrication materials which were prepared by the breath-figure method. The application of breath figures for the generation of all kinds of honeycomb is discussed.