MODULAR ASSEMBLY OF METAL-ORGANIC SUPER-CONTAINERS INCORPORATING CALIXARENES
A new strategy to design container molecules is presented. Sulfonylcalix[4]arenes, which are synthetic macrocyclic containers, are used as building blocks that are combined with various metal ions and tricarboxylate ligands to construct metal-organic ‘super-containers’ (MOSCs). These MOSCs possess both endo and exo cavities and thus mimic the structure of viruses. The synthesis of MOSCs is highly modular, robust, and predictable.
This application is a continuation of, and claims priority to, U.S. patent application Ser. No. 13/862,651 filed Apr. 15, 2013 and entitled “Modular Assembly of Metal-Organic Super-Containers Incorporating Calixarenes” and U.S. Provisional Application 61/686,868 filed Apr. 13, 2012 both of which are hereby incorporated by reference in their entirety under 35 U.S.C. §119(e).
GOVERNMENT SUPPORTThis invention was made with Government support under contracts DE-FG02-08ER64624 and DE-EE0000270 awarded by the Department of Energy; contract EPSCOR Grant No. 0903804 awarded by the National Science Foundation; and Grant No. 1352279 awarded by the National Science Foundation. The Government has certain rights to this invention.
BACKGROUND OF THE INVENTIONThe present invention relates generally to container molecules and, more specifically, to the modular assembly of metal-organic super-containers incorporating calixarenes generally and sulfonylcalixarenes and sulfinylcalixares, specifically.
Container molecules with well-defined hollow structures have attracted significant interest in recent years.1-11 These intriguing molecular receptors contain concave surfaces suitable for binding a variety of guests and offer unique chemical micro-environments relevant for a number of applications, including encapsulation of otherwise unstable species,12,13 promotion of chemical transformations,14-17 storage and separation of gases,9,18 transportation of small molecules,19,20 and templated formation of monodisperse nanoparticles.21 Nature has provided numerous elegant examples of supramolecular containers, such as viruses and other protein assemblies (e.g., ferritin), in which the highly organized structure of the biomolecules is key to their sophisticated function.22 Several research groups have presented a number of beautiful container systems that are based on covalent,1,8,9,12 coordination,3,5-7,10,11 or hydrogen bonding2,4,23 interactions. However, synthetic tools accessible to chemists for preparing molecular containers remain generally limited. Many artificial receptors have a relatively simple structure and few synthetic systems can match the function of their biological counterparts.
SUMMARY OF THE INVENTIONThe various implementations comprise a family of sulfonylcalixarene-incorporated metal-organic ‘super-containers’ (MOSCs) that mimic the topology of viruses. A series of synthetic containers are readily prepared via coordination-driven assembly of metal ions, carboxylate linkers, and sulfonylcalix[4]arenes. The synthesis of MOSCs is highly modular, robust, and predictable. The unique synthetic and structural features of MOSCs provide new opportunities for their functional applications.
The implementations also comprise a modular and robust approach to constructing synthetic receptors via coordination-driven assembling processes. These symmetric and highly unique coordination capsules contain both internal and surface cavities, a trademark feature of viruses, which use the enclosed space to store genetic materials (i.e., DNA or RNA) and the surface binding sites to recognize the specifically targeted hosts, respectively, a feature not previously exhibited in synthetic container systems.
One aspect relates to the ability to design the containers to a wide variety of desired structures and conformations. The containers comprise three components, namely, metal ions, organic linkers, and container pre-cursors. Each of the three components can be individually selected from a group of such components and used in building or synthesizing the compounds of the containers. The building or synthesis of the compounds is thus highly modular. In addition, the sizes of the internal and external cavities can likewise be precisely controlled by judicious selection of the building block components.
Another aspect is the diversity of container compounds that can be synthesized due to the modular nature of the building block components and synthesis process. Four separate classes of container shapes have been synthesized, representing containers that are face-directed octahedrons, edge-directed octahedrons, barrels, and cylinders.
Still another aspect is the structure-dependent properties of the novel molecules. The solubility and porosity of the molecules, in particular, appear to be dictated by the structural type or class they belong to such that the properties of the molecules, which are key to their applications, can be engineered by manipulating their structures.
Yet another aspect is that the molecules represent novel examples of soluble porous materials. Traditional adsorbents, such as zeolites and activated carbons, as well as newly emerging materials such as metal-organic frameworks, are solids that are almost insoluble in any solvent, which hampers their industrial applications. In contrast, the novel molecules described herein readily dissolve in common solvents and are highly solution-processable.
Another aspect is that the molecules demonstrate phase-dependent properties. The molecules can be easily handled in a solution form (i.e., 0-dimension), in a crystalline form (i.e., 3-dimension), and in a mono-layer form (i.e., 2-dimension). Interestingly, the same super-container molecule exhibits very different behavior depending on which phase it exists in.
These and other aspects will be understood and appreciated upon a review of this specification and drawings and the associated claims.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
Calixarenes are a versatile class of macrocyclic containers composed of phenolic units linked by methylene groups.29,30 Miyano and co-workers pioneered the efforts to synthesize thiacalixarenes, analogs of calixarenes in which methylene units are replaced by sulfur linkages (
More recently, the coordination chemistry of p-tert-butylsulfonylcalix[4]arene (H4TBSC) with metal ions and acetate was described.34 Tetranuclear cluster complexes were obtained via assembly of the quadruply deprotonated TBSC4− ligand, metal cations (e.g., Mn(II), Co(II), and Ni(II)), and acetate anions, where four phenoxo and four sulfonyl oxygen atoms coordinate to four metal ions that are further bound by four acetate groups and one μ4-hydroxo oxygen (
There are four prototypal containers that can be obtained, depending on whether the acetate ligand is replaced by a trigonal, linear, angular-planar, or angular-nonplanar carboxylate linker. These four container types can be rationalized as a face-directed octahedron (I), an edge-directed octahedron (II), a barrel (III) derived from truncating the face-directed octahedron, and a cylinder (IV), respectively (
Structures I-IV exemplify a novel design paradigm for the assembly of supramolecular containers, as it utilizes container molecules as building blocks in a manner that allows the creation of new enclosed hollow space (i.e., endo cavity) while retaining the free voids of the precursors (i.e., exo cavities). The resulting metal-organic super-containers (MOSCs) are of significant interest in the following ways: (1) the pore volume and widow size of the endo cavities can be tuned by choice of carboxylate ligands, whereas the exo cavities can be modified through variation of the sulfonylcalixarene units; (2) a wide variety of functionalities can be introduced through either metal ions or substitutions to sulfonylcalixarenes and carboxylates without affecting the prototypal MOSC structures; (3) the ternary nature of MOSCs affords a myriad of possibilities for structural and functional engineering; (4) the design of MOSCs, through linking the narrow lower rim of calixarene units, represents a new strategy to utilize calixarenes as building blocks.
All four prototypal MOSCs have been synthesized by combining p-tert-butylsulfonylcalix[4]arenes (TBSC), divalent metal ions (e.g., Mg(II), Ni(II), Co(II), etc.), and four types of carboxylate linkers, i.e., 1,3,5-benzenetricarboxylate (BTC), 1,4-benzenedicarboxylate (1,4-BDC), 1,3-benzenedicarboxylate (1,3-BDC), or 4,4′-methylenedibenzoate (MDB), under appropriate conditions (
Unless otherwise noted, starting materials and solvents were obtained from commercial suppliers (Fisher Scientific, TCI, Alfa Aesar, Cambridge Isotope Laboratories, Inc., etc.) and used without further purification. p-tert-Butylsulfonylcalix[4]arene (TBSC)40,41 was synthesized as described in the literature. Thermogravimetric analysis (TGA) was performed at a scan speed of 2° C./min under a stream of nitrogen on a TA INSTRUMENTS™ Q600 SDT. Typical sample size ranged from ˜5-10 mg. Gas and vapor adsorption isotherms were measured using a MICROMERITICS™ ASAP2020 instrument based on a volumetric method. Samples were typically washed with methanol and pre-dried on a Schlenk line at 120° C. for at least 8 h before transferred to pre-weighed analysis tubes which were then capped with seal frits. The samples were degassed under dynamic vacuum (<6 μmHg) at 105° C. for ˜24-48 h until the outgas rates were lower than 5 μmHg/min. The analysis tubes containing the evacuated samples were weighed again to determine the sample weights (typically ˜100 mg for most samples) before being transferred back to the analysis port of the instrument. The H2, N2 and O2 isotherms were measured at 77 K in a liquid N2 bath using ultra high pure (UHP) grade gases (99.99%), the CO2 isotherms were measured at 196 K in a dry ice/isopropanol bath using ultra high pure (UHP) grade CO2 gas (99.99%), and the MeOH and benzene isotherms were measured at 293 K in a water bath using the respective high purity vapor source (99.9%).
X-Ray Crystallography:
X-ray single-crystal diffraction data were collected at 100 K using graphite-monochromated Mo-Kα radiation (λ=0.71073 Å) on a BRUKER™ CCD APEXII diffractometer. The collected frames were processed with the software SAINT™.42 The data were corrected for absorption using the SADABS™ program.43 The structure was solved by the Direct methods (SHELX97)44 in conjunction with standard difference Fourier techniques and subsequently refined by full-matrix least-squares analyses on F2. Hydrogen atoms were generated in their idealized positions and all non-hydrogen atoms were refined anisotropically. The electron count due to disorder solvent in the void space of the crystals was calculated using the program SQUEEZE™ in PLATON™ software package.45
Dye Extraction.
Aqueous stock solutions of methylene blue (MB), rhodamine B (RB) and eosin Y (EY) were prepared by dissolving the corresponding dyes in deionized water. 5 mL of the aqueous dye solution (0.1×10−5-4×10−5 mol/L) was then added to 5 ml of a chloroform solution containing the MOSC (5×10−6 mol/L). The mixture was shaken for 1 min and kept in dark at room temperature for 4 h prior to the ultraviolet-visible (UV-Vis) measurements, allowing the aqueous and chloroform layers to fully separate. Control experiments were set up in a similar manner except the MOSC solutions were replaced by straight chloroform solvents.
The UV-Vis spectra of the aqueous and chloroform phases were recorded. The concentrations of MB, RB and EY in aqueous phases were directly determined on the basis of the absorbance at 664, 554, 517 nm, respectively, using previously determined calibration curves. The concentrations of the dyes in the chloroform phases were calculated by subtracting the remaining dye concentrations in the aqueous solutions from the dye concentrations of the aqueous stock solutions.
Synthesisp-tert-Butylsulfonylcalix[4]arene (H4TBSC)40, 41 and 1,3,5-benzenetribenzoic acid (H3BTB)46 were synthesized as described in the literature. De-p-tert-butylsulfonylcalix[4]arene (H4DTBSC) was obtained by the oxidation of de-p-tert-butylthiacalix[4] arene (H4DTCA)47.
De-p-tert-butylsulfonylcalix[4]arene (H4DTBSC):
To a solution of H4DTCA (0.74 g, 1.5 mmol) in chloroform (35 mL) were added acetic acid (50 mL) and NaBO3.4H2O (2.3 g, 15.0 mmol). The mixture was stirred at 50° C. for 24 h. After being cooled, 30 mL H2O was added. The white precipitate was collected by filtration, washed with water and chloroform, and dried under vacuum with heat. Yield: 0.81 g (86%). 1H NMR (200 MHz, d6-DMSO): δ=7.88 (d, 8H, J=8.0 Hz), 7.03 (t, 4H, J=7.2 Hz) ppm. 13C NMR (50 MHz, d6-DMSO): δ=158.2, 135.4, 130.7, 118.2 ppm.
MOSC-1-Ni:
Ni(NO3)2.6H2O (145.4 mg, 0.50 mmol), 1,3,5-benzenetricarboxylic acid (H3BTC) (69.3 mg, 0.33 mmol) and H4TBSC (84.9 mg, 0.10 mmol) were dissolved in 10 mL of N,N′-dimethylformamide (DMF) in a scintillation vial (20 mL capacity). The vial was placed in a sand bath, which was transferred to a programmable oven and heated at a rate of 0.5° C./min from 35 to 100° C. The temperature was held at 100° C. for 24 h before the oven was cooled at a rate of 0.2° C./min to a final temperature of 35° C. Green hexahedral crystals of MOSC-1-Ni were isolated by washing with DMF and CHCl3 and dried in the air to give 134 mg of the as-synthesized material.
MOSC-1-Mg:
MgCl2.6H2O (101.7 mg, 0.50 mmol), H3BTC (69.3 mg, 0.33 mmol) and H4TBSC (84.9 mg, 0.10 mmol) were dissolved in 10 mL of DMF in a scintillation vial (20 mL capacity). The vial was placed in a sand bath which was transferred to a programmable oven and heated at a rate of 0.5° C./min from 35 to 100° C. The temperature was held at 100° C. for 24 h before the oven was cooled at a rate of 0.2° C./min to a final temperature of 35° C. Colorless hexahedral crystals of MOSC-1-Mg were isolated by washing with DMF and CHCl3 and dried in the air to give 80 mg of the as-synthesized material.
MOSC-1-Co:
CoCl2.6H2O (119.0 mg, 0.50 mmol), H3BTC (69.3 mg, 0.33 mmol) and H4TBSC (84.9 mg, 0.10 mmol) were dissolved in 10 mL of DMF in a scintillation vial (20 mL capacity). The vial was placed in a sand bath which was transferred to a programmable oven and heated at a rate of 0.5° C./min from 35 to 100° C. The temperature was held at 100° C. for 24 h before the oven was cooled at a rate of 0.2° C./min to a final temperature of 35° C. Red crystals of MOSC-1-Co were isolated by washing with DMF and CHCl3 and dried in the air to give 109 mg of the as-synthesized material.
MOSC-2-Ni:
NiCl2.6H2O (118.9 mg, 0.50 mmol), H3BTC (69.4 mg, 0.33 mmol) and H4DTBSC (62.5 mg, 0.10 mmol) were dissolved in 10 mL of DMF in a scintillation vial (20 mL capacity). The vial was placed in a sand bath which was transferred to a programmable oven and heated at a rate of 0.5° C./min from 35 to 100° C. The temperature was held at 100° C. for 24 h before the oven was cooled at a rate of 0.2° C./min to a final temperature of 35° C. Green crystals of MOSC-2-Ni were isolated by washing with DMF and CHCl3 and dried in the air to give 92 mg of the as-synthesized material.
MOSC-3-Co:
CoCl2.6H2O (11.9 mg, 0.05 mmol), (1α,3α,5α)-1,3,5-cyclohexanetricarboxylic acid (H3CTC) (7.2 mg, 0.033 mmol) and H4DTBSC (6.3 mg, 0.01 mmol) were dissolved in 1 mL of DMF in a dram vial (4 mL capacity). The vial was placed in a sand bath which was transferred to a programmable oven and heated at a rate of 0.5° C./min from 35 to 100° C. The temperature was held at 100° C. for 24 h before the oven was cooled at a rate of 0.2° C./min to a final temperature of 35° C. Red crystals of MOSC-3-Co were isolated by washing with DMF and CHCl3 and dried in air to give 10 mg of the as-synthesized material.
MOSC-4-Co:
Co(NO3)2.6H2O (146 mg, 0.50 mmol), 1,3,5-benzenetribenzoic acid (H3BTB) (145 mg, 0.33 mmol) and H4TBSC (85.1 mg, 0.10 mmol) were dissolved in 12 mL of DMF in a scintillation vial (20 mL capacity). The vial was placed in a sand bath which was transferred to a programmable oven and heated at a rate of 0.5° C./min from 35 to 100° C. The temperature was held at 100° C. for 24 h before the oven was cooled at a rate of 0.2° C./min to a final temperature of 35° C. Red crystals of MOSC-4-Co were isolated by washing with DMF and CHCl3 and dried in air to give 85 mg of the as-synthesized material.
MOSC-III-tBu-Ni:
Ni(NO3)2.6H2O (72.7 mg, 0.25 mmol), 1,3-benzenedicarboxylic acid (1,3-BDC) (18.4 mg, 0.11 mmol) and TBSC (42.5 mg, 0.05 mmol) were dissolved in 10 mL of N,N-dimethylformamide (DMF) and 5 mL of methanol in a scintillation vial (20 mL capacity). The vial was placed in a sand bath, which was transferred to a programmable oven and heated at a rate of 0.5° C./min from 35 to 100° C. The temperature was held at 100° C. for 24 h before the oven was cooled at a rate of 0.2° C./min to a final temperature of 35° C. Green crystals of MOSC-III-tBu-Ni were isolated by washing with methanol and dried in the air to give 50.5 mg of the as-synthesized material.
MOSC-III-tBu-Co:
Co(NO3)2.6H2O (14.6 mg, 0.05 mmol), 1,3-BDC (3.7 mg, 0.022 mmol) and TBSC (8.5 mg, 0.01 mmol) were dissolved in 2 mL of DMF and 1 mL of methanol in a dram vial (4 mL capacity). The vial was placed in a sand bath, which was transferred to a programmable oven and heated at a rate of 0.5° C./min from 35 to 100° C. The temperature was held at 100° C. for 24 h before the oven was cooled at a rate of 0.2° C./min to a final temperature of 35° C. Pink crystals of MOSC-III-tBu-Co formed after 3 days and were isolated by washing with methanol and dried in the air to give 9.2 mg of the as-synthesized material.
MOSC-III′-tBu-Ni:
Ni(NO3)2.6H2O (72.7 mg, 0.25 mmol), chelidonic acid monohydrate (H2CA) (22.1 mg, 0.11 mmol), p-tert-butylsulfonylcalix[4]arene (H4TBSC) (43.1 mg, 0.05 mmol) and carbamazepine (75.2 mg, 0.31 mmol) were dissolved in 5 mL of DMF in a scintillation vial (20 mL capacity). The vial was placed in a sand bath, which was transferred to a programmable oven and heated at a rate of 0.5° C./min from 35 to 100° C. The temperature was held at 100° C. for 24 h before the oven was cooled at a rate of 0.2° C./min to a final temperature of 35° C. Green crystals of MOSC-III′-tBu-Ni were isolated by washing with methanol and dried in the air to give 45.2 mg of the as-synthesized material. The sample was typically further activated by drying on a Schlenk line at 120° C. for at least 8 h.
MOSC-III″-tBu-Ni:
Ni(NO3)2.6H2O (146.1 mg, 0.50 mmol), 5-sulfo-1,3-benzenedicarboxylic acid monolithium salt (5-SO3-1,3-BDC) (55.5 mg, 0.22 mmol) and TBSC (85.0 mg, 0.10 mmol) were dissolved in 10 mL of DMF in a scintillation vial (20 mL capacity). The vial was placed in a sand bath, which was transferred to a programmable oven and heated at a rate of 0.5° C./min from 35 to 100° C. The temperature was held at 100° C. for 24 h before the oven was cooled at a rate of 0.2° C./min to a final temperature of 35° C. Green crystals of MOSC-10-Ni were isolated by washing with methanol and dried in the air to give 62.5 mg of the as-synthesized material.
MOSC-IV-tBu-Co:
Co(NO3)2.6H2O (145.5 mg, 0.50 mmol), diphenylmethane-4,4′-dicarboxylic acid (H2DPMDC) (56.4 mg, 0.22 mmol) and p-tert-butylsulfonylcalix[4]arene (H4TBSC) (84.9 mg, 0.10 mmol) were dissolved in 12 mL of dimethylformamide (DMF). The solution was then evenly divided into ten 4-mL dram vials (1.2 mL each). The vials were placed in a sand bath, which was transferred to a programmable oven and heated at a rate of 0.5° C./min from 35 to 100° C. The temperature was held at 100° C. for 24 h before the oven was cooled at a rate of 0.2° C./min to a final temperature of 35° C. Red crystals of MOSC-IV-tBu-Co were isolated by washing with methanol and dried in the air to give a total of 50.2 mg of the as-synthesized material. The sample was typically further activated by drying on a Schlenk line at 120° C. for at least 8 h.
The resulting compounds were isolated in a highly crystalline form and fully characterized by a range of techniques including X-ray diffraction (XRD), thermal gravimetric analysis (TGA), elemental analysis, Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), nuclear magnetic resonance (NMR), mass spectrometry (MS), and gas/vapor adsorption.
The single-crystal XRD revealed that MOSC-1-Ni has a structure which consists of six tetranuclear complex units bridged by eight BTC ligands, mimicking the shape of an octahedron (
The TGA data (
This high chemical stability is probably due to the robust coordination backbone of the capsule as well as its favorable crystal packing. While the as-synthesized (i.e., solvated) MOSC-1-Ni crystals remain intact in most solvents, the evacuated (i.e., desolvated) sample is moderately soluble in CHCl3 and CH2Cl2, indicating the importance of solvation effects to achieving a higher solubility. Both UV-Vis and MS results suggest that MOSC-1-Ni molecules remain essentially intact in solution (data not shown).
With the successful synthesis of MOSC-1-Ni, the robustness of our design strategy and the ability to modify the capsule structure was examined. The first attempt was the synthesis of the container with other metal ions. When replacing Ni(II) in the initial reaction with Co(II) or Mg(II) salts, two isomorphic crystals, designated as MOSC-1-Co and MOSC-1-Mg, respectively, were obtained. These compounds have an identical capsule architecture and similar crystallographic features as MOSC-1-Ni (Tables 2 and 3).
The variation in metal ions appears to slightly modify several properties of the capsule, such as its thermal stability (data not shown). It is also worth noting that MOSC-1-Mg should be more suitable for solution studies by the nuclear magnetic resonance (NMR) technique than the other isomorphs thanks to the diamagnetic nature of Mg(II).
The feasibility of modifying the sulfonylcalix[4]arene unit in the container system was next evaluated. The synthetic chemistry of thiacalixarenes is relatively well established and functional groups at the p-position of the phenol residues can be readily manipulated.33 The compound de-p-tert-butyl-sulfonylcalix[4]arene (H4DTBSC) was chosen as an illustrative example. Upon replacing H4TBSC with H4DTBSC in the synthesis of MOSC-1-Ni, a new coordination super-container, designated as MOSC-2-Ni, was obtained. MOSC-2-Ni possesses a rather similar capsule framework as MOSC-1-Ni, but with an S6, instead of C4h, symmetry. The molecule is characterized by a slightly shortened inner diameter (ca.1.35 nm) and an appreciably reduced outer diameter (ca.2.5 nm) due to the absence of tert-butyl groups (
Finally, the possibility of varying the carboxylate linker was investigated. Attempts to substitute the rigid and planar H3BTC ligand with its more flexible counterpart, cis,cis-cyclohexane-1,3,5-tricarboxylic acid (H3CTC), led to the isolation of a new coordination capsule, MOSC-3-Co, which is derived from Co(II), DTBSC4−, and CTC3−. MOSC-3-Co is isomorphic to MOSC-2-Ni, i.e., the molecule has the same S6 symmetry and crystallizes in the same space group R
That expanded tri-carboxylate ligands afford similar MOSC structures with much larger endo cavities and more open portals was also investigated. Indeed, the reaction of Co(II), TBSC4−, and 1,3,5-benzenetribenzoate (BTB3−) generated an enlarged container, namely, MOSC-4-Co, which has an almost identical molecular and crystal symmetry as MOSC-1-Ni/Co/Mg (i.e., a point group of C4h and a space group of I4/m, respectively), but significantly increased dimensions (
Preliminary gas/vapor adsorption studies on the crystals of MOSCs indicate that the materials are permanently porous, although their sorption profiles do not follow that of a classic type I isotherm, and some of the MOSCs show interesting CO2/N2 selectivity. The Brunauer-Emmett-Teller (BET) surface area of MOSC-1-Ni is estimated to be ca. 230 m2/g based on the N2 adsorption isotherm at 77 K, while pronounced hysteresis is observed in all isotherms probed (i.e., N2 at 77 K, CO2 at 196 K, benzene and methanol at 293 K;
The X-ray crystal structure of MOSC-IV-tBu-Ni is particularly illustrative, as it highlights the dual-pore architecture of MOSCs and the unique opportunity it presents for host-guest binding (
The prototypal MOSCs can often be isolated as single-crystalline materials. As a result, X-ray crystallography is a powerful technique to characterize not only the molecular structure of MOSCs, but also the crystal packing that directly dictates their solid-state porosity. Indeed, single-crystal XRD study readily identifies two distinct crystal packing modes for type II MOSCs. While they have an almost identical container structure, MOSC-II-tBu-Co and MOSC-II-tBu-Ni crystallize in a different space group (I4/m vs. R
Most prototypal MOSCs appear to be permanently porous, although their gas/vapor adsorption profiles do not always follow that of a typical microporous material and often feature noticeable (sometimes pronounced) steps and hysteresis. This is clearly illustrated by the adsorption isotherms of a representative material, MOSC-III-tBu-Ni, which exhibits a 2-stepped or 3-stepped hysteresis in its N2 (77 K), O2 (77 K), and CO2 (196 K) sorption isotherms (
Another type II MOSC, namely, MOSC-II-tPen-Ni, which is an edge-directed octahedral MOSC decorated with tert-pentyl groups, shows a highly promising O2/N2 adsorption selectivity at 77 K. It adsorbs up to 100 cm3/g STP of O2 while taking up essentially none of N2 (
It is worth noting that MOSC-II-tPen-Co (i.e., the cobalt analogue), and MOSC-II-tBu-Ni or MOSC-II-tOc-Ni (i.e., the tert-butyl and tert-octyl analogues, respectively), which all share the same edge-directed octahedral container structure, show no such dramatic O2/N2 adsorption selectivity, as they adsorb O2 and N2 to either an equally significant degree, or an equally insignificant degree (
Several prototypal MOSCs have been found to be effective solid adsorbents for removing organic dyes from aqueous solutions. Adsorption studies by UV-Vis spectroscopy indicate that MOSC-II-tBu-Co has particularly encouraging separation capacity for methylene blue, taking up ca. 5 equivalents of the dye. Most intriguingly, the MOSC appears to selectively recognize methylene blue over Eosin Y, adsorbing very little of the latter even after days. The selectivity, without being bound, may be attributed to an ionic effect, since methylene blue is cationic and Eosin Y is anionic, or a size effect, as methylene blue is less bulky than Eosin Y. The methylene blue adsorption behavior of MOSC-II-tBu-Co, the tetragonal bcc phase, and MOSC-II-tBu-Ni, the rhombohedral fcc phase, deserves comparing. Although MOSC-II-tBu-Ni has a higher N2 adsorption capacity (
The possibility to tune the dye adsorption capacity of MOSCs can be further exemplified by a ligand functionalization strategy, which transforms a neutral MOSC, MOSC-III-tBu-Ni to an anionic MOSC, MOSC-III″-tBu-Ni, by replacing 1,3-BDC with a sulfo derivative, 5-sulfo-1,3-BDC. The two related MOSCs share a similar molecular framework and crystal packing (
A number of CHCl3-soluble MOSCs have shown distinctively different adsorption behavior at solid-liquid vs. liquid-liquid interfaces. The pentagonal MOSC-III′-tBu-Ni, for example, has an almost negligible adsorption capacity when the MOSC solid is placed in an aqueous solution containing methylene blue or Eosin Y even after hours. However, when the same MOSC is dissolved in CHCl3 and forms a liquid-liquid interface with an aqueous methylene blue solution, it instantly adsorbs and transfers the dye to the CHCl3 layer, whereas it remains ineffective for Eosin Y and does not adsorb it to any greater extent. The strikingly higher methylene blue adsorption in a liquid-liquid interface can be attributed to the much more accessible cavities of the fully dissolved MOSC. Remarkably, the adsorption of Eosin Y can be significantly enhanced in a co-adsorption manner when the liquid-liquid extraction is performed using a MOSC-III′-tBu-Ni solution pre-saturated with methylene blue. Since no significant increase of Eosin Y co-adsorption is observed when MOSC-III′-tBu-Ni is replaced by p-tert-butylsulfonylcalix[4]arene (data not shown), the enhancement of Eosin Y adsorption by the methylene blue saturated MOSC likely results from cooperative binding between the endo and exo cavities.
The foregoing description and drawings comprise illustrative embodiments of the various implementations. The foregoing embodiments and the methods described herein may vary based on the ability, experience, and preference of those skilled in the art. Merely listing the steps of the method in a certain order does not constitute any limitation on the order of the steps of the method. The foregoing description and drawings merely explain and illustrate the invention, and the invention is not limited thereto, except insofar as the claims are so limited. Those skilled in the art that have the disclosure before them will be able to make modifications and variations therein without departing from the scope of the invention.
Claims
1. A super-container molecule, comprising at least one metal-organic container molecule further comprising:
- a. sulfonylcalix[4]arenes;
- b. at least one metal ion;
- c. an organic ligand;
- d. at least one internal cavity; and
- e. at least one external cavity,
- wherein the sulfonylcalix[4]arenes are linked by the at least one metal ion, and
- wherein the organic ligand is a linker selected from the group consisting of 1,3,5-benzenetricarboxylate, 1,4-benzenedicarboxylate, 1,3-benzenedicarboxylate, and 4,4′-methylenedibenzoate.
2. The super-container of claim 1, wherein the metal-organic container molecule comprises at least four metal ions.
3. The super-container of claim 1, wherein the at least one metal ion is selected from the group consisting of divalent cations of transition metals and alkaline earth metals.
4. The super-container of claim 1, wherein the at least one metal ion is selected from the group consisting of cobalt, magnesium, manganese, and nickel.
5. The super-container of claim 1, further comprising an endo cavity.
6. The super-container of claim 1, wherein the linker comprises an exo binding domain.
7. A metal-organic super-container molecule, comprising:
- a. at least one internal cavity;
- b. at least one external cavity; and
- c. sulfonylcalix[4]arenes linked by metal ions and an organic linker;
- wherein the organic linker is a dicarboxylate linker having an edge-directed octahedral shape or a barrel shape; further wherein the dicarboxylate linker is 1,4-benzenedicarboxylate or 1,3-benzenedicarboxylate.
8. The metal-organic super-container molecule of claim 7, wherein the internal cavity further comprises a first internal cavity size, and the external cavity has a first external cavity size, and the first internal cavity size is increased by the dicarboxylate linker to a second, larger internal cavity size.
9. The metal-organic super-container molecule of claim 7, wherein the metal ions are selected from the group consisting of: cobalt, magnesium, manganese, and nickel.
10. The metal-organic super-container molecule of claim 7, wherein the structure of the container molecule is capable of being adjusted by substituting one or more of the sulfonylcalix[4]arenes, metal ions, or organic ligands.
11. The metal-organic super-container molecule of claim 7, wherein the molecule is capable of being adjusted to increase the size of the at least one internal cavity and at least one external cavity by substituting an expanded organic ligand.
12. A metal-organic super-container molecule, comprising:
- a. at least one internal cavity;
- b. at least one external cavity;
- c. a sulfonylcalix[4]arenes;
- d. at least one metal ion; and
- e. an aromatic dicarboxylate organic linker,
- wherein the aromatic dicarboxylate organic linker is selected from a group consisting of a linear-planar linker and an angular-planar linker.
13. The super-container of claim 12, wherein the super-container is formed by substituting the aromatic dicarboxylate organic linker for a mono-carboxylate organic ligand.
14. A super-container as defined in claim 12, wherein the functionality is selected from the group consisting of adsorptivity, porosity and solubility.
15. A super-container of claim 14, wherein the functionality is adsorbing a contaminant material from a liquid.
16. The super-container of claim 12, wherein the metal ions are selected from the group consisting of: cobalt, magnesium, manganese and nickel.
17. The super-container of claim 12, wherein the dicarboxylate organic linker is an angular-planar aromatic carboxylate linker.
18. The super-container of claim 17, wherein the angular-planar aromatic carboxylate linker is 1,3-benzenedicarboxylate.
19. The super-container of claim 12, wherein the dicarboxylate organic linker is a linear-planar aromatic carboxylate linker.
20. The super-container of claim 19, wherein the linear-planar aromatic carboxylate linker is 1,4-benzenedicarboxylate.
Type: Application
Filed: Aug 1, 2017
Publication Date: Nov 23, 2017
Inventors: Zhenqiang Wang (Vermillion, SD), Feng-Rong Dai (Vermillion, SD)
Application Number: 15/666,231