am9b05282_si_001.pdf (966.54 kB)
High Capacity Oil Denitrogenation over Azine- and Tetrazine-Decorated Metal–Organic Frameworks: Critical Roles of Hydrogen Bonding
journal contribution
posted on 2019-05-29, 00:00 authored by Sayed
Ali Akbar Razavi, Ali MorsaliIn this work, we
demonstrate that rational decoration of pore walls
of the metal–organic frameworks (MOFs) with azine and dihydro-tetrazine
functions is a very practical strategy for high capacity removal of
both neutral and basic nitrogen-containing compounds (NCCs) from model
oil. Its performance is even much better than the MOFs with high surface
area, open metal sites, and different functional groups such as amine,
hydroxyl, carboxy, and sulfonate. For this aim, a number of isostructure
functional MOFs (FMOFs) have been synthesized. Among them, TMU-5 (with
formula [Zn(OBA)(BPDH)0.5]n·1.5DMF, where H2OBA = 4,4′-oxybis(benzoic
acid) and BPDH = 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene) and TMU-34
(with formula [Zn(OBA)(H2DPT)0.5]n·DMF H2DPT = 3,6-di(pyridin-4-yl)-1,4-dihydro-1,2,4,5-tetrazine)
show high affinity toward neutral and basic NCCs, respectively. Dihydro-tetrazine-decorated
TMU-34 shows good affinity toward basic NCCs [pyridine (PYD) and quinoline
(QUI)] because of hydrogen bonding of dihydro-tetrazine (−NH)···(N)
basic NCCs. TMU-34 can adsorb about 619 and 632 mg g–1 PYD and QUI, respectively. On the other hand, azine-methyl-functionalized
TMU-5 shows very high affinity to neutral NCCs [pyrrole (PRR) and
indole (IND)] owing to strong hydrogen bonding of azine-methyl (Me–CN–NC–Me)···(NH)
neutral NCCs. TMU-5 can adsorb 518 and 578 mg g–1 PRR and IND, respectively. These numbers are among the best reported
data in this area and even reveal higher significance of the host–guest
interaction when we consider moderate surface of these FMOFs. These
results have been achieved by our “application-directed cavity
functionalization” approach through decoration of MOF structures
by suitable organic functional groups for specific purposes.