Porous organic polymers (POPs) have received increasing attention due to their properties, such as permanent porosity with tunable pore size, robust structure, high surface area, and versatility of the backbone...
Nanostructured
hypercrosslinked porous organic polymers have triggered
immense research interest for a broad spectrum of applications ranging
from catalysis to molecular separation. However, it still remains
a challenge to tune their nanoscale morphology. Herein, we demonstrated
a remarkable variation of morphologies of triptycene-based hypercrosslinked
microporous polymers starting from irregular aggregates (FCTP) to
rigid spheres (SCTP) to two-dimensional nanosheets (SKTP) from three
distinct polymerization methodologies, Friedel–Crafts knitting
using an external crosslinker, Scholl reaction, and solvent knitting,
respectively. Further, the dramatic role of reaction temperatures,
catalysts, and solvents resulting in well-defined morphologies was
elucidated. Mechanistic investigations coupled with microscopic and
computational studies revealed the evolution of 2D nanosheets of a
highly porous solvent-knitted polymer (SKTP, 2385 m2 g–1), resulting from the sequential hierarchical self-assembly
of nanospheres and nanoribbons. A structure–activity correlation
of hypercrosslinked polymers and their sulfonated counterparts for
the removal of toxic polar organic micropollutants from water was
delineated based on the chemical functionalities, specific surface
area, pore size distribution, dispersity, and nanoscale morphology.
Furthermore, a sulfonated 2D sheet-like solvent-knitted polymer (SKTPS)
exhibited rapid adsorption kinetics (within 30 s) for a large array
of polar organic micropollutants, including plastic components, steroids,
antibiotic drugs, herbicides, and pesticides with remarkable uptake
capacity and excellent recyclability. The current study provides the
impetus for designing morphology-controlled functionalized porous
polymers for task-specific applications.
Dynamic covalent chemistry (DCC) opens up a fascinating route for the construction of well‐organized supramolecular architectures, starting from organic molecular cages to crystalline macromolecular covalent organic frameworks (COFs). Herein, for the first time, we have manifested a facile room‐temperature DCC‐directed transformation of discrete organic imine cage‐to‐COF film at the liquid–liquid interface. The unfolding of the cage leading to the generation of imine intermediates, followed by their interface‐assisted preorganization and subsequent growth of the COF film, are elucidated through detailed spectroscopic and microscopic investigations. The interfacial cage‐to‐COF transformation provides a facile route for the faster fabrication of free‐standing COF films with high porosity and crystallinity, demonstrating excellent performance towards molecular sieving and high solvent permeance. Thus, the current study opens up a new route for structural interconversion between two crystalline entities with diverse dimensionality employing DCC at the confined interface.
Supramolecular
cavitands and organic cages having a well-defined
cavity and excellent host–guest complexing ability have been
explored for a myriad of applications ranging from catalysis to molecular
separation to drug delivery. On the other hand, porous organic polymers
(POPs) having tunable porosity and a robust network structure have
emerged as advanced materials for molecular storage, heterogeneous
catalysis, water purification, light harvesting, and energy storage.
A fruitful marriage between guest-responsive discrete porous supramolecular
hosts and highly porous organic polymers has created a new interface
in supramolecular chemistry and materials science, confronting the
challenges related to energy and the environment. In this mini-review,
we have addressed the recent advances (from 2015 to the middle of
2020) of cavitand and organic cage-based porous organic polymers for
sustainable development, including applications in heterogeneous catalysis,
CO2 conversion, micropollutant separation, and heavy metal
sequestration from water. We have highlighted the “cavitand/cage-to-framework”
design strategy and delineated the future scope of the emerging new
class of porous organic networks from “preporous” building
blocks.
The electrochromic materials have received immense attention for the fabrication of smart optoelectronic devices. The alteration of the redox states of the electroactive functionalities results in the color change in response to electrochemical potential. Even though transition metal oxides, redox‐active small organic molecules, conducting polymers, and metallopolymers are known for electrochromism, advanced materials demonstrating multicolor switching with fast response time and high durability are of increasing demand. Recently, two‐dimensional covalent organic frameworks (2D COFs) have been demonstrated as electrochromic materials due to their tunable redox functionalities with highly ordered structure and large specific surface area facilitating fast ion transport. Herein, we have discussed the mechanistic insights of electrochromism in 2D COFs and their structure‐property relationship in electrochromic performance. Furthermore, the state‐of‐the‐art knowledge for developing the electrochromic 2D COFs and their potential application in next‐generation display devices are highlighted.
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