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1.
Chem Commun (Camb) ; 2020 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-32588012

RESUMO

The pore space partition approach via post-synthetic linker insertion was used to modulate the porosity of a fragile Ag(i)-carboxylate framework with potentially large pore space. The resulting Ag(i)-MOFs with partitioned pores showed enhanced permanent porosity compared with a nonpartitioned Ag(i)-carboxylate framework.

2.
Chem Sci ; 10(22): 5801-5806, 2019 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-31293768

RESUMO

While the one-pot reaction of zirconium metal ions with a mixture of two dicarboxylate heterolinkers yielded a 12-c fcu Zr MOF with randomly distributed linkers, the symmetry-guided stepwise reaction produced the same MOF with both linkers precisely located in the framework. In the latter method, linear terephthalic acid (H2BDC) derivatives with mmm symmetry were inserted into the mmm-symmetry sites of the flexible Zr MOF with 8-c bcu topology (ZRN-bcu), which is composed of zigzag 2,6-naphthalenedicarboxylic acid with 2/m symmetry. Although the length of the symmetry-matching BDC2- derivatives was much shorter than the distance between the unlinked nearest-neighbor Zr clusters in ZRN-bcu, induced fitting of the derivatives into the framework was possible, resulting in well-defined locations for the two different dicarboxylate linkers. Thus, controlled synthesis of MOFs with the desired topology and functionality can be achieved using a symmetry-guided approach.

3.
Angew Chem Int Ed Engl ; 58(4): 1041-1045, 2019 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-30511777

RESUMO

Metal-organic polyhedra (MOP) are a promising class of crystalline porous materials with multifarious potential applications. Although MOPs and metal-organic frameworks (MOFs) have similar potential in terms of their intrinsic porosities and physicochemical properties, the exploitation of carboxylate MOPs is still rudimentary because of the lack of systematic development addressing their chemical stability. Herein we describe the fabrication of chemically robust carboxylate MOPs via outer-surface functionalization as an a priori methodology, to stabilize those MOPs system where metal-ligand bond is not so strong. Fine-tuning of hydrophobic shielding is key to attaining chemical inertness with retention of the framework integrity over a wide range of pH values, in strong acidic conditions, and in oxidizing and reducing media. These results are further corroborated by molecular modelling studies. Owing to the unprecedented transition from instability to a chemically ultra-stable regime using a rapid ambient-temperature gram-scale synthesis (within seconds), a prototype strategy towards chemically stable MOPs is reported.

4.
J Am Chem Soc ; 140(34): 10915-10920, 2018 08 29.
Artigo em Inglês | MEDLINE | ID: mdl-30086627

RESUMO

In systematic efforts toward a new type of molecule-based porous materials, facile and efficient synthetic methods have been established to obtain macrocyclic [Zr6]6 and supercage-like {[Zr6]6}8, where [Zr6] represents [Zr6O4(OH)4(CO2) n] building unit commonly found in Zr-based metal-organic frameworks. The reactions involve in situ hydrolysis of DMF solvent to produce formate linkers and thus do not require any organic ligand. A minor variation in the composition of two cyclic hexamers thus obtained results in dramatic differences in crystal packing which in turn lead to distinctive and selective sorption behavior for water vapor. It is shown that the high heat of water adsorption and unrestricted uptake under high humidity are consequences of the highly polar surface and flexible crystal packing. The reversibility of water adsorption is demonstrated by cyclic measurements of uptake and regeneration under dynamic flow conditions.

5.
Chem Commun (Camb) ; 54(67): 9360-9363, 2018 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-30079420

RESUMO

A highly robust porous hydrogen-bonded organic framework (HOF) constructed by 4,4',4''-benzene-1,3,5-triyl-tris(benzoic acid) not only achieves the highest uptakes of ethylene and ethane among the HOF materials, but also exhibits unusual adsorption selectivity of C2H6 over other C2 gases. Besides, it exhibits the second highest acetylene uptake among all the reported HOF materials.

6.
Inorg Chem ; 57(7): 3521-3528, 2018 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-29320171

RESUMO

Three-dimensional molecular architectures self-assembled with tripodal and tetratopic donors are valuable because of their encapsulation properties. Here, we present Co(I)-Fe(II)-Pd(II) heterotrimetallic trifacial barrel 1, which was self-assembled using a newly synthesized tetratopic donor [CpCo(CbR4)] [L; Cp = cyclopentadienyl, Cb = cyclobudiene, and R = 4-(4-pyridylphenyl)] and a 90° acceptor [ cis-(dppf)Pd(OTf)2] (A1; dppf = (diphenylphosphino)ferrocene and OTf = CF3SO3-). The heterotrimetallic barrel 1 exhibited selective 1:1 interaction with a N, N'-dimethyl-1,4,5,8-naphthalenetetracarboxylic diimide guest, as revealed by 1H NMR analysis. The self-assembly of donor L with two other Ru(II)-based 180° acceptors [( p-cymene)2Ru2(OO∩OO)(OTf)2] [OO∩OO = 6,11-dioxido-5,12-naphthacenedione (A2) and oxalate (A3)] resulted in tetragonal-prismatic cages. Self-assembly using the longer acceptor A2 provided rare isomers of a tetragonal-prismatic cage by varying the orientation of the cyclopentadienyl moiety out-out (2a) or out-in (2b) of the cavity, whereas self-assembly using the shorter acceptor A3 selectively resulted in the tetragonal-prismatic cage 3. The three-dimensional molecular architectures 1-3 were characterized by combined spectroscopic and elemental analyses. The structures of molecular barrel 1 and prismatic cage 3 were elucidated by single-crystal X-ray analysis.

7.
Dalton Trans ; 47(7): 2415-2421, 2018 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-29379928

RESUMO

Heteroleptic titanium alkoxides with three different ligands, i.e., [Ti(OiPr)(X)(Y)] (X = tridentate, Y = bidentate ligands), were synthesized to find efficient metal organic chemical vapor deposition (MOCVD) precursors for TiO2 thin films. Acetylacetone (acacH) or 2,2,6,6-tetramethyl-3,5-heptanedione (thdH) was employed as a bidentate ligand, while N-methyldiethanolamine (MDEA) was employed as a tridentate ligand. It was expected that the oxygen and moisture susceptibility of titanium alkoxides, as well as their tendency to form oligomers, would be greatly reduced by placing multidentate and bulky ligands around the center Ti atom. The synthesized heteroleptic titanium alkoxides were characterized both physicochemically and crystallographically, and their thermal behaviors were also investigated. [Ti(OiPr)(MDEA)(thd)] was found to be monomeric and stable against moisture; it also showed good volatility in the temperature window between volatilization and decomposition. This material was used as a single-source precursor during MOCVD to generate TiO2 thin films on silicon wafers. The high thermal stability of [Ti(OiPr)(MDEA)(thd)] enabled the fabrication of TiO2 films over a wide temperature range, with steady growth rates between 500 and 800 °C.

8.
Nat Commun ; 8(1): 1599, 2017 11 17.
Artigo em Inglês | MEDLINE | ID: mdl-29150596

RESUMO

Solid-state reaction of organic molecules holds a considerable advantage over liquid-phase processes in the manufacturing industry. However, the research progress in exploring this benefit is largely staggering, which leaves few liquid-phase systems to work with. Here, we show a synthetic protocol for the formation of a three-dimensional porous organic network via solid-state explosion of organic single crystals. The explosive reaction is realized by the Bergman reaction (cycloaromatization) of three enediyne groups on 2,3,6,7,14,15-hexaethynyl-9,10-dihydro-9,10-[1,2]benzenoanthracene. The origin of the explosion is systematically studied using single-crystal X-ray diffraction and differential scanning calorimetry, along with high-speed camera and density functional theory calculations. The results suggest that the solid-state explosion is triggered by an abrupt change in lattice energy induced by release of primer molecules in the 2,3,6,7,14,15-hexaethynyl-9,10-dihydro-9,10-[1,2]benzenoanthracene crystal lattice.

9.
Dalton Trans ; 46(19): 6146-6158, 2017 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-28332680

RESUMO

Various fabrication strategies for hollow metal-organic framework (MOF) superstructures are reviewed and classified using various types of external templates and their properties. Hollow MOF superstructures have also been prepared without external templates, wherein unstable intermediates obtained during reactions convert to the final hollow MOF superstructures. Many hollow MOF superstructures have been fabricated using hard templates. After the core-shell core@MOF structure was prepared using a hard template, the core was selectively etched to generate a hollow MOF superstructure. Another approach for generating hollow superstructures is to use a solid reactant as a sacrificial template; this method requires no additional etching process. Soft templates such as discontinuous liquid/emulsion droplets and gas bubbles in a continuous soft phase have also been employed to prepare hollow MOF superstructures.

10.
Sci Rep ; 7: 41447, 2017 01 27.
Artigo em Inglês | MEDLINE | ID: mdl-28128298

RESUMO

The MOF with the encapsulated CO2 molecule shows that the CO2 molecule is ligated to the unsaturated Cu(II) sites in the cage using its Lewis basic oxygen atom via an angular η1-(OA) coordination mode and also interacts with Lewis basic nitrogen atoms of the tetrazole ligands using its Lewis acidic carbon atom. Temperature dependent structure analyses indicate the simultaneous weakening of both interactions as temperature increases. Infrared spectroscopy of the MOF confirmed that the CO2 interaction with the framework is temperature dependent. The strength of the interaction is correlated to the separation of the two bending peaks of the bound CO2 rather than the frequency shift of the asymmetric stretching peak from that of free CO2. The encapsulated CO2 in the cage is weakly interacting with the framework at around ambient temperatures and can have proper orientation for wiggling out of the cage through the narrow portals so that the reversible uptake can take place. On the other hand, the CO2 in the cage is restrained at a specific orientation at 195 K since it interacts with the framework strong enough using the multiple interaction sites so that adsorption process is slightly restricted and desorption process is almost clogged.

11.
ACS Omega ; 2(9): 5486-5493, 2017 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31457817

RESUMO

A new series of heteroleptic complexes of cobalt were synthesized using aminoalkoxide and ß-diketonate ligands. The complexes, [Co(dmamp)(acac)]2 (3), [Co(dmamp)(tfac)]2 (4), [Co(dmamp)(hfac)]2 (5), [Co(dmamp)(tmhd)]2 (6), and [Co(dmamb)(tmhd)]2 (7), were prepared by two-step substitution reactions and studied using Fourier transform infrared spectroscopy, mass spectrometry, elemental analysis, and thermogravimetric analysis (TGA). Complexes 3-7 displayed dimeric molecular structures for all of the complexes with cobalt metal centers interconnected by µ2-O bonding by the alkoxy oxygen atom. TGA and a thermal study of the complexes displayed high volatilities and stabilities for complexes 6 and 7, with sublimation temperatures of 120 °C/0.5 Torr and 130 °C/0.5 Torr, respectively.

12.
Dalton Trans ; 46(2): 571-577, 2017 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-27977025

RESUMO

This paper reports the formation of unprecedented iridium(iii)-derived topological macrocycles. Discrete molecular Borromean rings 1 and 3 in pure form are synthesized via coordination-driven self-assembly of an acceptor [(Cp*Ir)2(OO∩OO)](OTf)2 (Cp* = pentamethylcyclopentadienyl, OO∩OO = 6,11-dioxido-5,12-naphthacenedione) (A) with dipyridyl donors 1,4-bis(4-pyridinylethynyl)benzene (L1) and 2,5-bis(4-pyridinylethynyl)thiophene (L2) respectively in methanol. Self-assembly using the same acceptor under similar conditions with two other donors 9,10-bis(4-pyridinylethynyl)anthracene (L3) and 1,4-di(4-pyridinylethynyl)buta-1,3-diyne (L4) resulted in [2]catenane 5 and non-catenane ring-in-ring topological macrocycle 7 respectively. Rectangular macrocycles 2, 4, 6, and 8 were respectively obtained when the self-assembly of acceptor A with one of the donors L1-L4 was carried out under dilute conditions in nitromethane or methanol. All these new macrocycles were characterized by 1H and 13C NMR, 2D NMR, ESI-MS and elemental analyses. Single crystal X-ray structures of Borromean rings 1 and 3, and ring-in-ring macrocycle 7 revealed that the length and functionality of donors enabling CHπ and ππ interactions govern the topology.

13.
Sci Rep ; 6: 30123, 2016 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-27444513

RESUMO

Since the aliphatic C-H···anion interaction is relatively weak, anion binding using hydrophobic aliphatic C-H (Cali-H) groups has generally been considered not possible without the presence of additional binding sites that contain stronger interactions to the anion. Herein, we report X-ray structures of organic crystals that feature a chloride anion bound exclusively by hydrophobic Cali-H groups. An X-ray structure of imidazolium-based scaffolds using Cali-H···A(-) interactions (A(-) = anion) shows that a halide anion is directly interacting with fifteen Cali-H groups (involving eleven hydrogen bonds, two bidentate hydrogen-bond-type binding interactions and two weakly hydrogen-bonding-like binding interactions). Additional supporting interactions and/or other binding sites are not observed. We note that such types of complexes may not be rare since such high numbers of binding sites for an anion are also found in analogous tetraalkylammonium complexes. The Cali-H···A(-) interactions are driven by the formation of a near-spherical dipole layer shell structure around the anion. The alternating layers of electrostatic charge around the anion arise because the repulsions between weakly positively charged H atoms are reduced by the presence of the weakly negatively charged C atoms connected to H atoms.

14.
Proc Natl Acad Sci U S A ; 113(27): 7414-9, 2016 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-27313207

RESUMO

The formation of 2D polyaniline (PANI) has attracted considerable interest due to its expected electronic and optoelectronic properties. Although PANI was discovered over 150 y ago, obtaining an atomically well-defined 2D PANI framework has been a longstanding challenge. Here, we describe the synthesis of 2D PANI via the direct pyrolysis of hexaaminobenzene trihydrochloride single crystals in solid state. The 2D PANI consists of three phenyl rings sharing six nitrogen atoms, and its structural unit has the empirical formula of C3N. The topological and electronic structures of the 2D PANI were revealed by scanning tunneling microscopy and scanning tunneling spectroscopy combined with a first-principle density functional theory calculation. The electronic properties of pristine 2D PANI films (undoped) showed ambipolar behaviors with a Dirac point of -37 V and an average conductivity of 0.72 S/cm. After doping with hydrochloric acid, the conductivity jumped to 1.41 × 10(3) S/cm, which is the highest value for doped PANI reported to date. Although the structure of 2D PANI is analogous to graphene, it contains uniformly distributed nitrogen atoms for multifunctionality; hence, we anticipate that 2D PANI has strong potential, from wet chemistry to device applications, beyond linear PANI and other 2D materials.

15.
Angew Chem Int Ed Engl ; 55(26): 7413-7, 2016 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-27119651

RESUMO

Solid-state reactions have been rapidly gaining popularity in organic chemistry owing to their simplicity, efficiency, and selectivity compared to liquid-phase reactions. Herein, we describe the formation of superstructures through the solid-state reaction of an organic single-crystal. The superstructure of 5,5',5''-(1,3,5-triazine-2,4,6-triyl)triisophthalonitrile (TIPN) can be formed by cyclotrimerization of 1,3,5-tricyanobenzene (TCB) single crystals. The TIPN superstructure was confirmed by single crystal X-ray diffraction and visualized by transmission electron microscopy. The superstructure has hexagonally packed 1-dimensional (1D) channels along the crystal axis. Furthermore, the superstructure arises from interdigitated nitrile interactions in the crystal lattice, and thus has electron-beam tolerance and very high thermal stability.

16.
Dalton Trans ; 44(31): 14042-53, 2015 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-26166756

RESUMO

Heteroleptic complexes of strontium () were prepared by employing ß-diketonates and donor-functionalized alkoxides as coordinating ligands. The results illustrate the effect of alkoxide substituent groups on the overall structures of the complexes. The presence of a terminal methoxy group in the alkoxide ligands leads to the formation of trimeric complexes , whereas the substituents on the amine nitrogen prove to have less influence in determining the structure. The attempts to increase steric bulkiness of the aminoalkoxide ligands by introducing ethyl groups on the amine nitrogen and to the alkoxy carbon did not lead to a structural change from the dimeric form in but resulted in structurally interesting strontium complexes. In trimeric complexes , the three strontium atoms were held together by two µ3-O bonds using alkoxide oxygen atoms and two µ2-O bonds using a combination of alkoxide and ß-diketonate ligand oxygens. The strontium metal centers in these complexes exhibit seven-coordination states in and , whereas exhibits one six-coordinated and two seven-coordinated strontium metals in its structure. All of the complexes were characterized using FT-NMR, FT-IR, elemental analyses, and thermogravimetric (TG) analyses.

17.
Chem Commun (Camb) ; 51(17): 3678-81, 2015 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-25643825

RESUMO

Single crystalline hollow metal-organic frameworks (MOFs) with cavity dimensions on the order of several micrometers and hundreds of micrometers were prepared using a metal-organic polyhedron single crystal as a sacrificial hard template. The hollow nature of the MOF crystal was confirmed by scanning electron microscopy of the crystal sliced using a focused ion beam.

18.
Chem Commun (Camb) ; 51(21): 4492-5, 2015 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-25682749

RESUMO

A hollow iridium-cornered prismatic cage was self-assembled without the assistance of any template. The cage was found to be capable of encapsulating heteroguest's triplet in its perfect sized cavity, producing the first demonstration of quintuple structure by an octahedral metal cornered prismatic cage.


Assuntos
Complexos de Coordenação/química , Irídio/química , Cristalografia por Raios X , Espectroscopia de Ressonância Magnética , Conformação Molecular , Nanoestruturas/química , Tamanho da Partícula
19.
Chem Soc Rev ; 43(16): 6141-72, 2014 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-25009001

RESUMO

In this review, we describe two recently implemented conceptual approaches facilitating the design and deliberate construction of metal­organic frameworks (MOFs), namely supermolecular building block (SBB) and supermolecular building layer (SBL) approaches. Our main objective is to offer an appropriate means to assist/aid chemists and material designers alike to rationally construct desired functional MOF materials, made-to-order MOFs. We introduce the concept of net-coded building units (net-cBUs), where precise embedded geometrical information codes uniquely and matchlessly a selected net, as a compelling route for the rational design of MOFs. This concept is based on employing pre-selected 0-periodic metal­organic polyhedra or 2-periodic metal­organic layers, SBBs or SBLs respectively, as a pathway to access the requisite net-cBUs. In this review, inspired by our success with the original rht-MOF, we extrapolated our strategy to other known MOFs via their deconstruction into more elaborate building units (namely polyhedra or layers) to (i) elucidate the unique relationship between edge-transitive polyhedra or layers and minimal edge-transitive 3-periodic nets, and (ii) illustrate the potential of the SBB and SBL approaches as a rational pathway for the design and construction of 3-periodic MOFs. Using this design strategy, we have also identified several new hypothetical MOFs which are synthetically targetable.

20.
Dalton Trans ; 43(38): 14461-9, 2014 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-24984199

RESUMO

A series of heteroleptic strontium complexes (1-9) using a combination of different aminoalkoxides and 2,2,6,6-tetramethyl-3,5-heptanedionate (tmhd) were prepared to examine the effect of the bulkiness and coordination ability of the aminoalkoxide ligand in these complexes as well as potential strontium precursors. All complexes were characterized by FT-IR, FT-NMR, elemental analyses, and thermo-gravimetric (TG) analyses. The crystal structure analyses of 1, 2, 4, and 5 demonstrate their stability in the dimer form and the unwillingness of the strontium atom to form more than six coordination bonds in these complexes. The complex 5 shows an unusual picture: the existence of one hexa-coordinated and one penta-coordinated strontium atom side by side in its dimer structure. The introduction of ether groups as coordination sites in complexes 6-9 led to a decrease in steric hindrance which resulted in the formation of the complex 7 as a tetramer. The complex 7 shows a unique Sr4O4 cubane core where oxygen atoms undergo µ3-bridging between strontium atoms. The TG analyses show that the complexes exhibit a step-wise decomposition character, with the major mass losses in the region 150-400 °C.

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