Design, synthesis, characterization, and sorption properties of metal-organic frameworks and polyhedra based on [iron(3)oxide(R dioxide)(6)L(3)](0/+) clusters.

Abstract

This thesis reports the synthesis and single crystal X-ray structures of iron-carboxylate metal-organic frameworks (MOFs), Fe(<italic>p</italic>-BDC)(DMF)&middot;(H₂O)₂ (MOF-220) (<italic>a</italic> = 19.4697(13), <italic> b</italic> = 7.2493(5), <italic>c</italic> = 8.7730(6) A, <italic>Pnma </italic>) Fe₃(BTC)₂(H₂O)&middot;(H₂O)₁₁(DMF)₄ (MOF-225) (<italic>a</italic> = 26.7472(9) A, <italic>Fm</italic>3&macr;<italic>m</italic>), Fe(BPDC)(DMF)&middot;(DMF)_0.5 (MOF-106) (<italic>a</italic> = 7.124(4), <italic>b</italic> = 15.270(2), <italic> c</italic> = 12.0109(17) A, beta = 94.604(2)&deg;, <italic>C</italic>2/<italic> c</italic>) and Fe₂(<italic>m</italic>-BDC)₂ (DMF)₃&middot;(DMF)(H₂O) (MOF-230) (<italic>a</italic> = 18.341(2), <italic> b</italic> = 10.0356(11), <italic>c</italic> = 18.039(2) A, <italic> Pca</italic>2₁), composed of square (Fe₂(CO₂)₄), infinite rod (Fe(CO₂)₄), and tetrahedral (Fe₂(CO₂)₄) building units. A second series of related reactions revealed a method for controlling structure periodicity by sulfate-capped vertices, which resulted in formation of isostructural, discrete, metal-organic polyhedra (MOPS) of the general formula, Fe₁₈O₉(TDC)₆(SO₄)₉(OH)₃(DMF)₁₅(RO)₃&middot;G (MOPs-100, 101, and 103),(R = ethyl, 1-propyl, or 1-pentyl). The non-capped version of the Fe₃O(RO₂)₆ (R = carbon or sulfur) trigonal prismatic building unit was linked by ditopic benzene links to produce two 3-periodic frameworks, [Fe₃O(<italic> p</italic>-BDC)₃(DMF)₃][FeCl₄]&middot;(DMF)₃ (MOF-235) (<italic>a</italic> = 12.531(3), <italic>c</italic> = 18.476(11) A, <italic>P</italic>6&macr;2<italic>c</italic>) and [Fe₃O(<italic> m</italic>-BDC)₃(pyr)₃]&middot;(pyr)_0.5(H₂O)_1.5 (MOF-236) (<italic>a</italic> = 13.017(4), <italic> c</italic> = 14.896(8) A, <italic>P</italic>6&macr;2<italic>c</italic>), having a new topology termed <bold>acs</bold>. Three sites of the trigonal prismatic unit can alternately be capped with sulfate to yield the triangular unit, Fe₃O(SO₄)₃(CO₂)₃. This was joined by either ditopic (phenyl, biphenyl, terphenyl, or hydropyrene) or tritopic (benzenetriphenyl) links to give the isostructural truncated tetrahedra and truncated heterocubane of general formula, [NH₂(CH₃)₂]₈[Fe₁₂O₄(SO₄)₁₂(link)<italic>_x</italic>(py)₁₂]&middot;G (<italic>x</italic> = 6 for linear or 4 for trigonal), respectively (<italic>a</italic> = 32.6504(13) A, <italic> F</italic>4&macr;3<italic>m</italic> for IRMOP-50) (<italic>a</italic> = 25.8626(9), <italic> b</italic> = 26.8359(9), <italic>c</italic> = 28.1926(10) A, alpha = 75.1380(10)&deg;, beta = 88.5680(10)&deg;, gamma = 63.7830(10)&deg;, <italic> P</italic>1&macr; for triclinic IRMOP-51) (<italic>a</italic> = 38.508(9) A, <italic>F</italic>4&macr;3<italic>m</italic> for cubic IRMOP-51) (<italic>a</italic> = 43.730(4), <italic>b</italic> = 22.671(2), <italic> c</italic> = 41.328(4) A, beta = 120.182(2)&deg;, <italic>C</italic>2/<italic> c</italic> for IRMOP-52) (<italic>a</italic> = 31.642(3), <italic>b</italic> = 31.762(3), <italic>c</italic> = 31.830(3) A, alpha = 75.847(2)&deg;, beta = 75.264(2)&deg;, gamma = 60.155(2)&deg;, <italic>P</italic>1&macr; for IRMOP-53) (<italic>a</italic> = 26.8549(13), <italic>c</italic> = 40.9221(19) A, <italic>I</italic>4₁/<italic>a</italic> for MOP-54). These MOPs can be linked further by bifunctional 1,2-bis-4-pyridylethane to give a three-periodic MOF [NH₂(CH₃)₂]₈[Fe₁₂O₄(SO₄)₁₂(BPDC)₆(bpe)₆]&middot;G (MOF-500) (<italic>a</italic> = 38.641(6) A, <italic>F</italic>4&macr;3<italic>m</italic>). Truncated tetrahedral and truncated heterocubiodal MOPs show porosity and uptake of N₂, CO₂, Ar, H₂, CH₄, and benzene. The isotherms exhibit Type I behavior, indicative of permanent microporosity with apparent surface areas ranging from 387 to 480 m<super> 2</super>/g.