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Metal chalcogenides

The layered metal sulfides with the general formula K2xMxSn3-xS6 (x = 0.5– 0.95) (M= Mn, KMS-1; M = Mg, KMS-2) represent examples of metal sulfides with clay-type ion exchange properties. These compounds have unique characteristics compared to conventional layered ion exchanged materials such as clays. For example, they show a remarkable selectivity for Sr2+ even under highly alkaline (5M NaOH) or acidic conditions, which make the materials promising for nuclear waste remediation. For comparison, clays are active as Sr2+ sorbents only within a narrow pH range (4-10). The reason for the high Sr2+ affinity of KMS materials under acidic conditions is the presence of soft basic sites, the S2- ligands, which display small affinity for hard proton ions. Thus, the Sr2+ exchange for KMS has limited interference from H+, in contrast to the exchange properties of oxidic materials ‘poisoned’ by proton ions. Under highly alkaline conditions, Sr2+ exists primarily as the relatively soft [Sr(OH)]+, which can be preferably sorbed by KMS-1 over the hard Na+ ions. The results of this research were published in the prestigious journal Proc. Nat. Acad. Sci. U.S.A. and were also advertised by various scientific websites [Chemistry world (RSC), MRS.org (Materials Research Society), Chemie.De, Northwestern News Center, Αrgonne National Laboratory News etc] and science news journals (C&En News, European Commission DG ENV News). The same KMS materials have also shown interesting and selective Cs+ exchange properties, which were described in a publication in J. Am. Chem. Soc. However, the property of KMS materials that distinguish them among all known sorbents is their ability to sequester heavy metal ions from water. Through detailed studies, presented in a publication in Chem. Eur. J., it was demonstrated that KMS-1 and 2 materials are superior heavy metal ion sorbents over known materials. KMS-1/2 are relatively inexpensive and can rapidly reduce the Hg2+, Pb2+, and Cd2+ content of aqueous media well below the acceptable limits for water. Thus, these materials are promising for the detoxification of a variety of wastes and drinking water from heavy metal ions. More recently, an unusual capability of KMS-1 to absorb UO22+, even traces existing in seawater, has been reported in a publication in J. Am. Chem. Soc. All the results of the synthesis and ion-exchange properties of KMS materials were also included in a patent.

 

References:

  1. M. J. Manos, N. Ding, M. G. Kanatzidis, “Layered metal sulfides: Exceptionally selective agents for radioactive strontium removal”, Proc. Nat. Acad. Sci. U.S.A. 2008, 105, 3696.

  2. M. J. Manos, M. G. Kanatzidis, “Highly efficient and rapid Cs uptake by the layered sulphide KMS-1”, J. Am. Chem. Soc.  2009, 131, 6599.

  3. M. J. Manos, V. G. Petkov, M. G. Kanatzidis, “H2xMnxSn3-xS6 (x= 0.11-0.25): A novel reusable sorbent for highly specific mercury capture under extreme pH conditions”, Adv. Funct. Mater. 2009, 19, 1087.

  4. M. J. Manos, M. G. Kanatzidis, “Sequestration of heavy metals from water with layered metal sulphides”, Chem. Eur. J. 2009, 15, 4479. 

  5. M. J. Manos, M. G. Kanatzidis, “Layered metal sulfides capture uranium from seawater”, J. Am. Chem. Soc. 2012, 134, 16441.

  6. J.  L. Mertz, Z. H. Fard, C. Malliakas, M. J. Manos, M. G. Kanatzidis, “Selective removal of Cs+, Sr2+, and Ni2+ by K2xMgxSn3−xS6 (x = 0.5−1) (KMS-2) relevant to nuclear waste remediation”, Chem. Mater. 2013, 25, 2116.

  7. M. J. Manos, N. Ding, M. G. Kanatzidis, “New chalcogenide compound for treatment of wastes with extremely low yet highly toxic mercury concentrations”, Patent Number: WO2009048552-A1; US2009095684-A1; US8070959-B2.

  8. ​M. J. Manos, Mercouri G. Kanatzidis, "Metal sulfide ion exchangers: superior sorbents for the capture of toxic and nuclear waste-related metal ions", Chem. Sci. 2016, 7, 4804 (Perspective article).

Metal Organic Frameworks-Exploratory synthesis

  • Metal organic frameworks (MOFs) based on new types of nanosized ligands, such as Zn4O(L)2 (UCY-1) with very high surface areas (up to 2500 m2/g) and significant CO2 uptake and selectivity (work published in Inorganic Chemistry) as well as a Cd2+ MOF (UCY-3) with large liquid benzene sorption capacity (cover article in CrystEngComm).

  • New synthetic strategies to obtain MOFs with novel structural types, for example by using a combination of trimesic acid and various aminoalcohols (work published in Cryst. Growth. Des.)  

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References:

 

  1. M. J. Manos, M. S. Markoulides, C. D. Malliakas, G. S. Papaefstathiou,  N. Chronakis, M. G. Kanatzidis, P. N. Trikalitis, A. J. Tasiopoulos, “A highly porous interpenetrated metal-organic framework from the use of a novel nanosized organic Linker”, ”, Inorg. Chem. 2011, 50, 11297.

  2. E. J. Kyprianidou, G. S. Papaefstathiou, M. J. Manos,* A. J. Tasiopoulos, “A flexible Cd2+ metal organic framework with a unique (3,3,6)-connected topology, unprecedented secondary building units and single crystal to single crystal solvent exchange properties”, CrysEngComm 2012,14, 8368 (*one of the corresponding authors). 

  3. M. J. Manos, E. E. Moushi, G. S. Papaefstathiou, A. J. Tasiopoulos, “New Zn2+ metal organic frameworks with unique network topologies from the combination of trimesic acid and amino-alcohols”, Cryst. Growth Des. 2012, 12, 5471.  

  • Synthesis of new Lanthanide MOFs with extraordinary single-crystal-to-single-crystal (SCSC) coordinating solvent exchange properties. SCSC solvent exchange is not only important because of the fundamental interest of SCSC transformations, but also because this exchange of coordinating solvent ligands can be an efficient method to functionalize MOFs and tune their properties. Thus, via the coordinating solvent exchange, for the first time MOFs with free –SH were prepared with a rational method (work published in Inorganic Chemistry). In addition, results that have been submitted for publication indicate that a significant enhancement of the photoluminescent properties of lanthanide MOFs may be achieved by the SCSC coordinating solvent exchange.

  • Lanthanide MOFs as highly selective sorbents for small organic molecules. The capability of flexible lanthanide MOFs as highly selective MeOH sorbents in the liquid phase, a property which is of interest for the removal of MeOH impurities from bioethanol, was recently demonstrated (work published in J. Mater. Chem. A).

    References: 

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  1. M. J. Manos, E. J. Kyprianidou, G. S. Papaefstathiou, A. J. Tasiopoulos, “Insertion of functional groups into a Nd3+ metal-organic framework via single-crystal-to-single-crystal coordinating solvent exchange”, Inorg. Chem. 2012, 51, 6308.

  2. C. G. Efthymiou, E. J. Kyprianidou, C. J. Milios, M. J. Manos*, A. J. Tasiopoulos, “Flexible lanthanide MOFs as highly selective and reusable liquid MeOH sorbents”, J. Mater. Chem. A, 2013, 1, 5061.  (*one of the corresponding authors).

 

 

  • Synthesis of new MOFs from a combination of inorganic and organic ligands with interesting structures and gas sorption properties. We have recently reported a porous copper-trimesate selenite compound, which shows a robust 3-D porous structure with unprecedented structural characteristics and represents a unique example of a metal inorganic-organic framework with considerable permanent microporosity and selective CO2 sorption property.

  • Synthesis of new  alkaline earth metal ion frameworks (AEMOFs) with interesting luminescence properties. We have reported a Mg2+ MOF (AEMOF-1), which exhibits the remarkable capability to rapidly detect traces of water (0.05–5% v/v) in various organic solvents through an unusual turn-on luminescence sensing mechanism. The extraordinary sensitivity and fast response of this MOF for water, and its reusability make it one of the most powerful water sensors known. In addition, a series of alkaline earth metal ion/dihydroxy−terephthalate metal organic frameworks (AEMOFs) has been isolated. The reported AEMOFs display a number of new structural features and unusual luminescent properties such as a strong dependence of emission wavelength on the alkaline earth ion and a bathochromic shift of their emission at low temperature. Remarkably, the Ba2+ MOF shows rare yellow fluorescence, particularly attractive for solid state lighting applications. 

  • Single crystal-to-single-crystal cation exchange in AEMOFs. More recently we reported a microporous Mg2+ MOF with capability for partial exchange of Mg2+ by Cu2+ in single-crystal-to-single-crystal fashion.

 

References

1.G. S. Papaefstathiou, K. S. Subrahmanyam, G.. S. Armatas, C.. D. Malliakas, M. G. Kanatzidis, Manolis. J. Manos,* “A unique microporous copper-trimesateselenite with high selectivity for CO2”, CrystEngComm 2014, 16, 3483.

2. Antigoni Douvali, Athanassios C. Tsipis, Svetlana V. Eliseeva, Stphane Petoud, Giannis S. Papaefstathiou, Christos D. Malliakas, Ioannis Papadas, Gerasimos S. Armatas, Irene Margiolaki, Mercouri G. Kanatzidis, Theodore Lazarides,* and Manolis J. Manos*, " Turn-On Luminescence Sensing and Real-Time Detection of Traces of Water in Organic Solvents by a Flexible Metal–Organic Framework", Angew. Chem. Int. Ed. 2015, 54, 1651.

3.A. Douvali, G. S. Papaefstathiou, M. P. Gullo, A. Barbieri, A. C. Tsipis, C. D. Malliakas, M. G. Kanatzidis, I. Papadas, G. S. Armatas, A. G. Hatzidimitriou, T. Lazarides*, Manolis J. Manos*, "Alkaline Earth Metal Ion/Dihydroxy–Terephthalate MOFs: Structural Diversity and Unusual Luminescent Properties", Inorg. Chem. 2015, 54, 5813.

4.E. Papazoi,   A. Douvali,   S. Rapti,  E. Skliri,   G. S. Armatas,  G. S. Papaefstathiou,   X. Wang,  Z.-F. Huang ,   S. Kaziannis,  C. Kosmidis,   A. Hatzidimitriou,  T. Lazarides, M. J. Manos   “A microporous Mg2+ MOF with cation exchange properties in a single-crystal-to-single-crystal fashion” Inorg. Chem. Front. 2017 (in press, DOI:  10.1039/C6QI00548A) (Themed Collection: In honour of Mercouri G. Kanatzidis for his contributions to Inorganic Chemistry for over 30 years).

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MOF and MOF-organic polymer composites for water treatment

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  • We recently reported an anion exchange composite material based on a protonated amine-functionalized metal organic framework, called Metal Organic Resin-1 (MOR-1), and alginic acid (HA). MOR-1-HA material shows an exceptional capability to rapidly and selectively sorb Cr(VI) under a variety of conditions and in the presence of several competitive ions. The selectivity of MOR-1-HA for Cr(VI) is shown to be the result of strong O3CrVI∙∙∙NH2 interactions. The composite sorbent can be successfully utilized in an ion-exchange column, in contrast to pristine MOR-1 which forms fine suspensions in water passing through the column. Remarkably, an ion exchange column with only 1% wt. MOR-1-HA and 99% wt. sand (an inert and inexpensive material) is capable of reducing moderate and trace Cr(VI) concentrations well-below the acceptable safety limits for water. The relatively low cost of MOR-1-HA/sand column and its high regeneration capability and reusability make it particularly attractive for application in the remediation of Cr(VI)-bearing industrial waste.

  • We also described a new synthetic method for the isolation of the UiO-66 amino-functionalized material (called as metal organic resin-1, MOR-1) and its composite with alginic acid (HA). MOR-1  can be prepared in high yield  (~70%) and purity within an hour via a reflux reaction of ZrCl4 and 2-amino-terephthalic acid in acifidied aqueous solution, whereas addition of sodium alginate to the fine suspension of MOR-1 resulted from the reflux synthesis affords the MOR-1-HA composite. This inexpensive, green and fast preparation method results in  UiO-66 amino-functionalized materials (MOR-1 and MOR-1-HA) of the same quality and microporous features as those of compounds isolated with the slower solvothermal synthesis involving toxic and costly organic solvents. Field Emission-Scanning Electron Microscopy (FE-SEM) studies revealed that MOR-1 consists of spongy nanoparticles  (150-300 nm in size), whereas MOR-1-HA nanoparticles are relatively compact. Thus, for the first time we could visualize the effect of alginic acid partially coating the surface of the MOR particles. The composite prepared with this method can be successfully utilized as stationary phase, mixed with sand, in anion-exchange column. The column shows excellent  hexavalent chromium sorption properties  and can be easily regenarated and reused several times with almost no loss of its initial Cr(VI)  removal capacity. Remarkably, this ion exchange column is capable  of eliminating Cr(VI) ions from chrome plating wastewater samples, thus indicating its potential for applications in industrial wastewater.

  • We also report a new microporous metal–organic framework (MOF) H16[Zr6O16(H2PATP)4]Cl8xH2O (H2PATP = 2-((pyridin-1-ium-2-ylmethyl)ammonio)terephthalate), denoted as MOR-2 (metal organic resin-2). MOR-2 represents the first Zr4+-terephthalate MOF with an 8-connected net and also the first example where a bulky functional group was introduced into the terephthalate scaffold prior to the MOF synthesis.
    MOR-2 shows extraordinary capability to rapidly capture (within 1 min) hexavalent chromium with a sorption capacity up to 194 mg Cr(VI) per g, which far exceeds those reported for the known Cr(VI) sorbents. Moreover, MOR-2 in its composite form with alginic acid (HA) can be utilized in ion exchange columns, which are highly efficient for the removal of Cr(VI) from aqueous solutions including industrial waste samples and also can be regenerated and reused several times with minimal loss (<20%) of their capacity. Besides an excellent sorbent, MOR-2 is also a highly efficient sensor for real time detection of Cr(VI) species as revealed by fluorescence titration experiments in acidic aqueous media. The Cr(VI)
    detection limits were found as low as 4 ppb, while the system exhibited excellent sensitivity when real world, instead of standard, samples were employed. Thus, the MOR-2 material is a unique example combining both excellent sorption and exceptional luminescence sensing of Cr(VI) species in aqueous solutions.

  • More recently we describe the sorption properties of [Zr6O4(OH)4(NH3 +-BDC)6]Cl6$xH2O (MOR-1) and H16[Zr6O16(H2PATP)4]Cl8.xH2O
    (MOR-2) towards ReO4-  and TcO4-. Both MOR-1 and MOR-2 are very effective sorbents for ReO4- and TcO4- anions, with MOR-2 showing the highest sorption capacity (up to 4.1 mmol/g) among the known metal organic materials. Importantly, the exceptional sorption capacity of MOR-2 is retained even under conditions simulating acidic nuclear waste. In addition, MOR-1 and MOR-2 exhibit selective luminescence ReO4- sensing properties, demonstrated for the first time for MOF materials.

 

 

See our recent papers

1. S. Rapti,   A. Pournara,   D. Sarma,  I. Papadas,   G. S. Armatas,   A. Tsipis,  T. Lazarides,   M. Kanatzidis, Manolis J. Manos*, “Selective capture of hexavalent chromium from an anion-exchange column of metal organic resin-alginic acid composite”, Chem. Sci., 2016, 7, 2427.

2. S. Rapti,   A. Pournara,   D. Sarma,  I. Papadas,   G. S. Armatas;   Y. S. Hassan, M. H. Alkordi, M. G.   Kanatzidis, M. J.  Manos*, “Rapid, green and inexpensive synthesis of high quality UiO-66 amino-functionalized materials with exceptional capability for removal of hexavalent chromium from industrial waste”, Inorg. Chem. Front. 2016, 3, 635 (Themed Collection: Emerging Investigators-Hot article).

3. S. Rapti, D. Sarma,S. Diamantis, E. Skliri, G. S. Armatas, A. Tsipis, Y. S. Hassan, M. H. Alkordi, C. D. Malliakas, M. Kanatzidis, T. Lazarides*, J. C. Plakatouras*, M. J. Manos*, “All in one porous material:Exceptional sorption and selective sensing of hexavalent chromium by a Zr4+ MOF”, J. Mater. Chem. A, 2017, 5, 14707.

4. S. Rapti,  S. A. Diamantis, A. Dafnomili, A. Pournara, E. Skliri, G. S. Armatas, A. C. Tsipis, I. Spanopoulos, C. D. Malliakas, M. G. Kanatzidis, J. C. Plakatouras*, F. Noli*, T. Lazarides*, M. J. Manos*, “Exceptional TcO4- sorption capacity and highly efficient ReO4- luminescence sensing by Zr4+ MOFs”, J. Mater. Chem. A, 2018 (Advance Article, DOI: 10.1039/C8TA07901C).

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MOF-modified electrodes  for determination of heavy metals

 

 

 

 

 

 

 

 

 

 

 

 

 

We recently discovered that the Ca2+ two-dimensional framework, namely [Ca(H4L)(DMA)2]·2DMA (Ca-MOF) was capable of exchanging the Ca2+ ions by Cu2+ almost quantitatively in a matter of seconds in aqueous solution. Herein, we report that the Ca-MOF exhibits capability for both removal and voltammetric determination of heavy metal ions in aqueous media. Ca-MOF shows one of the highest Pb2+ sorption capacities (~522 mg g-1) reported for MOFs. More importantly, a column filled with Ca-MOF (1% wt.) particles dispersed in silica sand (99% wt.) can quantitatively remove traces of Pb2+ (~100 ppb) from a relatively large volume of a wastewater simulant solution (containing large excess of competitive ions). Ca-MOF is also highly efficient for sorption of Cd2+, Ni2+ and Zn2+, even in the presence of several competitive cations. Actually, the Cd2+ sorption capacity (~220 mg g-1) of Ca-MOF is one of the largest reported for MOFs. Furthermore, detailed Ni2+ and Zn2+ sorption studies of MOFs have not been described prior to this work.  The mechanism of the M2+ (M2+= Pb2+, Cd2+, Ni2+, Zn2+) exchange process was elucidated based on a series of spectroscopic, analytical and X-ray diffraction methods. In addition, a simple ready-to-use electrochemical sensor based on modified graphite paste with Ca-MOF was fabricated and successfully utilized for the determination of Pb2+, Cd2+, Cu2+ and Zn2+ at µg L-1 levels in aqueous solutions by anodic stripping voltammetry (ASV).  Overall, this work demonstrates, for the first time, a dual function of a MOF as a sorbent and as an electrochemical sensor for heavy metal ions, thus opening a new window for materials with appllication in both envirnomental remediation and monitoring.

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See our recent papers:

1.  A. D. Pournara, A. Margariti, G. D. Tarlas, A. Kourtelaris, V. Petkov, C. Kokkinos, A. Economou, G. S. Papaefstathiou*, M. J. Manos*, “A Ca2+ MOF combining highly efficient sorption and capability for voltammetric determination of heavy metal ions in aqueous media”, J. Mater. Chem. A, 2019, 7, 15432.

2.A. D. Pournara, G. D. Tarlas, G. S. Papaefstathiou, M. J. Manos*, “Chemically modified electrodes by MOFs for the determination of inorganic and organic analytes via voltammetric techniques: A critical review”, Inorg. Chem. Front., 2019, DOI: 10.1039/C9QI00965E.

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