Covalent organic frameworks (COFs), because of their ordered pores and crystalline structure, become designable polymers for charge storage applications. Supercapacitors are critical in developing hybrid energy devices. Amalgamating these high-surface-area frameworks in the capacitor assembly can aid develop robust solid-state supercapacitors. Here, we present supercapacitors drawn on three closely related pyridyl-hydroxyl functionalized COFs. The keto-enol tautomerism and the hydrogen bonding ability of the hydroxyl units promise added chemical stability in this potentially hydrolyzable Schiff-bonded COF. Meanwhile, the pyridyl and triazine groups ensure rapid charge storage by reversibly interacting with protons from the acidic electrolyte. The COF with the highest surface area, as expected, yields an excellent specific capacitance of 546 F/g at 500 mA/g in acidic solution and ∼92 mF/cm2 at 0.5 mA/cm2 in the solid-state device, which is the highest among all the COF-derived solid-state capacitors, which is reflected by a high power density of 98 μW/cm2 at 0.5 mA/cm2, most of which is retained even after 10 000 cycles. This high activity comes from a smooth electrical-double-layer-capacitance favored by an ordered-porous structure and some pseudo-capacitance assisted by the participation of redox-active functional groups. The study highlights the by-design development of COFs for superior energy/charge devices.

Fe 2+ is vital to O 2 transportation and photosynthesis regulated by oxidases and reductases. On the other hand, Fe 3+ is detrimental due to its irreversible binding to O 2 . Hence there is a need for selective identification of Fe 3+ from aqueous systems in the presence of Fe 2+ . However, given their close chemical nature, it is not straightforward to differentiate them. Fe 2+ and Fe 3+ are typically sensed and differentiated using magnetic measurements, Mossbauer, X-ray absorption spectroscopy, or EXAFS, which are complex and equipment intensive techniques. In comparison, the fluorescence technique is advantageous in terms of time and accessibility. Although readily available lanthanide salts exhibit fluorescence, they are weak, and to serve as an optical probe, their luminescence has to be enhanced via ligand design. Hence we have designed a chromophoric ligand that can covalently bind to lanthanides and enhance its fluorescence intensity, and it binds selectively to Fe 3+ through its nitrogen centers. It detects Fe 3+ from low concentration (∼100 μM) aqueous solutions, with fast response time (<1 min) and with a detection limit of 3.6 ppm. Importantly, the Fe 3+ adsorbed MOF can be readily reactivated for the next cycle by merely washing with an aqueous ascorbic acid solution and can be used for multiple cycles without any appreciable loss in activity. This makes the Ln-MOF an environmentally benign, cost-effective, scalable, and recyclable probe.

This article explains the need for energy-efficient large-scale CO2 capture and briefly mentions the requirements for optimal solid sorbents for this application.

Here, we present a new ultramicroporous Cu paddlewheel based MOF. This ultramicroporous MOF has most of the features such as porosity (BET surface area = 945 m/g), CO capacity (3.5 mmol/g at ambient temperature and pressure), CO/N selectivity (sCO/N = 250), and fast CO diffusion kinetics ( D = 2.25 × 10 m/s), comparable to some of the other high-performing ultramicroporous MOFs, with strong binding sites. Typically, such MOFs exhibit strong CO-framework interactions (evidenced from a heat of adsorption ≥ 38 kJ/mol). However, the MOF explained here, despite having channels lined by the amine and the open-metal sites, possesses only a moderate CO-framework interaction (HOA = 26 kJ/mol). Using periodic DFT, we have probed this counterintuitive observation.

Here, we report two novel water-stable aminefunctionalized MOFs,n amely IISERP-MOF26 ([NH 2 (CH 3 , which show selective CO 2 capture capabilities.T hey are made by combining inexpensive and readily availablet erephthalic acid and N-rich adeninew ithC ua nd Zn, respectively.T hey possess 1D channels decoratedb yt he free amine group from the adenine and the polarizing oxygen atoms from the terephthalate units. Even more, there are dimethyl ammonium (DMA + )c ationsi nt he pore rendering an electrostatic environmentw ithin the channels. The activated Cu-andZ n-MOFs physisorb about 2.7 and 2.2 mmol g À1 of CO 2 ,r espec-tively,w ith high CO 2 /N 2 and moderate CO 2 /CH 4 selectivity. The calculated heat of adsorption (HOA = 21-23 kJ mol À1 )f or the CO 2 in both MOFs suggest optimal physical interactions which corroborate well with their facile on-off cycling of CO 2 .N otably,b oth MOFs retain their crystallinity and porosity even after soaking in water for 24 hours as well as upon exposure to steam over 24 hours. The exceptional thermal and chemical stability,f avorable CO 2 uptakes and selectivity and low HOA make these MOFs promising sorbents for selective CO 2 capture applications.H owever,t he MOF'sl ow heat of adsorption despite having ah ighly CO 2 -loving groups lined walls is quite intriguing.