Hydrophobization of metal-organic frameworks (MOFs) is important to push forwardt heir practical use and thus has attracted increasing interest. In contrast to the previous reports,w hich mainly focused on the modification of organic ligands in MOFs,h erein, we reported an ovel strategy to decorate the metal-oxo nodes of MOFs with phenylsilane to affords uper-hydrophobic NH 2 -UiO-66(Zr), which shows highly improved base resistance and holds great promise in versatile applications,s uch as organic/water separation, selfcleaning,a nd liquid-marble fabrication. This work demonstrates the first attempt at metal-oxon ode modification for super-hydrophobic MOFs,a dvancing an ew concept in the design of MOFs with controlled wettability for practical applications.Smart solid materials with special surface wettability are being sought owing to their diverse potential applications. [1,2] Super-hydrophobic porous materials are of interest since they can provide both aw ater-repellent surface and inherent porosity,w hich enable them to be used for some special applications,s uch as contaminatedwater treatments and fuel purification. [3,4] Metal-organic frameworks (MOFs) constructed from metal-oxo nodes interconnected by polydentate organic ligands are ac rystalline porous materials which have shown great promise in various applications. [5][6][7][8][9][10][11][12][13] Recent research has involved preparing hydrophobic MOFs,n ot only to combat their failure in applications under humid conditions,b ut also endow them with improved or even novel functional properties. [14][15][16][17][18][19][20][21][22][23][24][25] Enabled by the designable and flexible features of MOFs,decorating MOFs with hydrophobic moieties has been widely used for imparting hydrophobicity to MOFs.E ncouraging progress has been made in improving the water-repelling capacity of MOFs by functionalizing the organic ligands with hydrophobic groups. [25][26][27][28] Surprisingly,t here is no attempt to design the metal-oxo nodes for functional hydrophobic MOFs,i ns pite of their easily modified nature. [26][27][28][29][30][31] In addition, the intrinsic presence of metal-OH groups at metal-oxo nodes of MOFs enables af acile and direct decoration process, [30,32] offering advantages over the ligand modification process that requires extra functional groups as "tags" for post modification steps.Herein we initiated an attempt to prepare super-hydrophobic MOFs by modification of the metal-oxo nodes.N H 2functionalized MOFs have attracted interest owing to their unique properties distinguished from the bare MOFs.N H 2 -UiO-66(Zr) represents one of the most appealing MOFs showing great potential in different applications and was thus selected. [28,31,[33][34][35][36] Phenylsilane (PhSiH 3 )was grafted onto the Zr-O metal-oxo nodes of NH 2 -UiO-66(Zr) by allowing it to react with the Zr-OH groups,e xposing the hydrophobic phenyl groups to form the super-hydrophobic NH 2 -UiO-66(Zr) (NH 2 -UiO-66(Zr)-shp) with ah igh water contact angle of 1618 8 (Scheme 1). Thet hus ...
An operationally simple and high yielding protocol for the synthesis of polyfunctional pyrazoles has been developed through one-pot, three-component coupling of aldehydes, 1,3-dicarbonyls, and diazo compounds as well as tosyl hydrazones. The reaction proceeds through a tandem Knoevenagel condensation, 1,3-dipolar cycloaddition, and transition metal-free oxidative aromatization reaction sequence utilizing molecular oxygen as a green oxidant. The scope of the reaction was studied by varying the aldehyde, 1,3-dicarbonyl, and diazo component individually.
An operationally simple, one-pot, two-step cascade method has been developed to afford biologically important fused 1,2,3-triazolo-heterocyclic scaffolds from 2-alkynyl aryl(heteroaryl) aldehydes and phenacyl azides. This unique atom economical transformation engages four reactive centers (aldehyde, alkyne, active methylene, and azide) under metal-free catalysis.
A novel strategy for the synthesis of imidazo[1,2-a]pyridines via efficient catalyst/metal-free annulations of α-keto vinyl azides and 2-aminopyridines is described. Several imidazo[1,2-a]pyridines were synthesized from readily available vinyl azides and 2-aminopyridines and obtained in highly pure form by simply evaporating the reaction solvent. This remarkably high yielding and atom economical protocol allows the formation of three new C-N bonds through cascade reactions and rearrangements.
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