Adsorbents with stepped isotherms for gas storage applications

An adsorbent having a stepped isotherm comprising a flexible metal-organic framework which has repeating cores comprising the formula M-L-M, wherein L is a linking moiety comprising a structure of Formula I:

• wherein,
• X1-X6 are each independently a C or a N;
• R1-R2 and R7-R8 are each independently selected from the group consisting of H, D, optionally substituted C1-C3 alkyl, optionally substituted C1-C3 alkenyl, halo, hydroxyl, aldehyde, carboxyl, amine, nitrile, azide, and nitro;
• R3-R6 are each independently selected from the group consisting of H, D, FG, optionally substituted (C1-C12)alkyl, optionally substituted hetero-(C1-C12)alkyl, optionally substituted (C2-C12)alkenyl, optionally substituted hetero-(C1-C12)alkenyl, optionally substituted (C2-C12)alkynyl, optionally substituted hetero-(C2-C12)alkynyl, optionally substituted cycloalkyl, optionally substituted cycloalkenyl, optionally substituted aryl, optionally substituted heterocycle, optionally substituted mixed ring system, —C(R11)3, —CH(R11)2, —CH2R11, —C(R12)3, —CH(R12)2, —CH2R12, —OC(R11)3, OCH(R11)2, —OCH2R11, —OC(R12)3, —OCH(R12)2, OCH2R12, and adjacent R groups can be linked together to form an optionally substituted ring;
• R11 is selected from the group consisting of FG, optionally substituted (C1-C12)alkyl, optionally substituted hetero-(C1-C12)alkyl, optionally substituted (C1-C12)alkenyl, optionally substituted hetero-(C1-C12)alkenyl, optionally substituted (C1-C12)alkynyl, optionally substituted hetero-(C1-C12)alkynyl;
• and
• R12 is selected from the group consisting of cycloalkyl, aryl and heterocycle;
• and wherein
• M is selected from the group consisting of Be2+, Mg2+, Ca2+, Sr2+, Ba2+, Sc2+, Y2+, Ti2+, Zr2+, V2+, Nb2+, Ta2+, Cr2+, Mo2+, W2+, Re2+, Fe2+, Ru2+, Os2+, Rh2+, Ir2+, Ni2+, Pd2+, Pt2+, Cu2+, Ag2+, Au2+, Hg2+, Al2, In2+, Si2+, Ge2+, Sn2+, Pb2+, As2+, Te2+, La2+, Ce2+, Pr2+, Nd2+, Sm2+, Eu2+, Gd2+, Tb2+, Db2+, Tm2+, Yb2+, La2+, and combinations thereof, including any complexes which contain the metals or metal ions, as well as any corresponding metal salt counter-anions;
• wherein tetrahedrally or pseudo-tetrahedrally M is bridged by μ2-pyrazolate units of L;
• and
• wherein M is selected from the croup consisting of Mg2+, Ca2+, Ba2+, Zr2+, V2+, Cr2+, Mo2+, W2+, Fe2+, Ni2+, Cu2+, and Ce2+.