TY - JOUR

T1 - Tailoring porosity and rotational dynamics in a series of octacarboxylate metal-organic frameworks

AU - Moreau, Florian

AU - Kolokolov, Daniil I.

AU - Stepanov, Alexander G.

AU - Easun, Timothy L.

AU - Dailly, Anne

AU - Lewis, William

AU - Blake, Alexander J.

AU - Nowell, Harriott

AU - Lennox, Matthew J.

AU - Besley, Elena

AU - Yang, Sihai

AU - Schröder, Martin

PY - 2017/3/21

Y1 - 2017/3/21

N2 - Modulation and precise control of porosity of metal-organic frameworks (MOFs) is of critical importance to their materials function. Here we report modulation of porosity for a series of isoreticular octacarboxylate MOFs, denoted MFM-180 to MFM-185, via a strategy of selective elongation of metal-organic cages. Owing to the high ligand connectivity, these MOFs do not show interpenetration, and are robust structures that have permanent porosity. Interestingly, activated MFM-185a shows a high Brunauer-Emmett-Teller (BET) surface area of 4,734 m2 g-1 for an octacarboxylate MOF. These MOFs show remarkable CH4 and CO2 adsorption properties, notably with simultaneously high gravimetric and volumetric deliverable CH4 capacities of 0.24 g g-1 and 163 vol/vol (298 K, 5-65 bar) recorded for MFM-185a due to selective elongation of tubular cages. The dynamics of molecular rotors in deuterated MFM-180a-d16 and MFM- 181a-d16 were investigated by variable-temperature 2H solid-state NMR spectroscopy to reveal the reorientation mechanisms within these materials. Analysis of the flipping modes of the mobile phenyl groups, their rotational rates, and transition temperatures paves the way to controlling and understanding the role of molecular rotors through design of organic linkers within porous MOF materials.

AB - Modulation and precise control of porosity of metal-organic frameworks (MOFs) is of critical importance to their materials function. Here we report modulation of porosity for a series of isoreticular octacarboxylate MOFs, denoted MFM-180 to MFM-185, via a strategy of selective elongation of metal-organic cages. Owing to the high ligand connectivity, these MOFs do not show interpenetration, and are robust structures that have permanent porosity. Interestingly, activated MFM-185a shows a high Brunauer-Emmett-Teller (BET) surface area of 4,734 m2 g-1 for an octacarboxylate MOF. These MOFs show remarkable CH4 and CO2 adsorption properties, notably with simultaneously high gravimetric and volumetric deliverable CH4 capacities of 0.24 g g-1 and 163 vol/vol (298 K, 5-65 bar) recorded for MFM-185a due to selective elongation of tubular cages. The dynamics of molecular rotors in deuterated MFM-180a-d16 and MFM- 181a-d16 were investigated by variable-temperature 2H solid-state NMR spectroscopy to reveal the reorientation mechanisms within these materials. Analysis of the flipping modes of the mobile phenyl groups, their rotational rates, and transition temperatures paves the way to controlling and understanding the role of molecular rotors through design of organic linkers within porous MOF materials.

KW - CH

KW - CO

KW - Copper

KW - Metal-organic framework

KW - Molecular rotors

KW - STORAGE

KW - POROUS COORDINATION POLYMERS

KW - molecular rotors

KW - BUILDING-BLOCKS

KW - MOLECULAR ROTORS

KW - CO2

KW - TEREPHTHALATE PHENYLENES

KW - ADSORPTION

KW - CH4

KW - metal-organic framework

KW - FUNCTIONALIZATION

KW - HYDROGEN

KW - copper

KW - LIGAND

KW - CARBON-DIOXIDE

UR - http://www.scopus.com/inward/record.url?scp=85016102050&partnerID=8YFLogxK

U2 - 10.1073/pnas.1615172114

DO - 10.1073/pnas.1615172114

M3 - Article

C2 - 28280097

AN - SCOPUS:85016102050

VL - 114

SP - 3056

EP - 3061

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 12

ER -