Abstract: Primary, secondary (1°,2°) alkylethylenediamine- and alkylpropylenediamine-appended variants of metal-organic framework are provided for CO2 capture applications. Increasing the size of the alkyl group on the secondary amine enhances the stability to diamine volatilization from the metal sites. Two-step adsorption/desorption profiles are overcome by minimzing steric interactions between adjacent ammonium carbamate chains. For instance, the isoreticularly expanded framework Mg2(dotpdc) (dotpdc4?=4,4?-dioxido-[1,1?:4?,1?-terphenyl]-3,3?-dicarboxylate), yields diamine-appended adsorbents displaying a single CO2 adsorption step. Further, use of the isomeric framework Mg-IRMOF-74-II or Mg2(pc-dobpdc) (pc-dobpdc4?=3,3-dioxidobiphenyl-4,4-dicarboxylate, pc=para-carboxylate) also leads to a single CO2 adsorption step with bulky diamines.

Abstract: Primary, secondary (1°,2°) alkylethylenediamine- and alkylpropylenediamine-appended variants of metal-organic framework are provided for CO2 capture applications. Increasing the size of the alkyl group on the secondary amine enhances the stability to diamine volatilization from the metal sites. Two-step adsorption/desorption profiles are overcome by minimzing steric interactions between adjacent ammonium carbamate chains. For instance, the isoreticularly expanded framework Mg2(dotpdc) (dotpdc4?=4,4?-dioxido-[1,1?:4?,1?-terphenyl]-3,3?-dicarboxylate), yields diamine-appended adsorbents displaying a single CO2 adsorption step. Further, use of the isomeric framework Mg-IRMOF-74-II or Mg2(pc-dobpdc) (pc-dobpdc4?=3,3-dioxidobiphenyl-4,4-dicarboxylate, pc=para-carboxylate) also leads to a single CO2 adsorption step with bulky diamines.

Abstract: Polyamines with lengths carefully tailored to the framework dimensions are appended to metal-organic frameworks such as Mg2(dobpdc) (dobpdc4-=4,4?-dioxidobiphenyl-3,3?-dicarboxylate) with the desired loading of one polyamine per two metal sites. The polyamine-appended materials show step-shaped adsorption and desorption profiles due to a cooperative CO2 adsorption/desorption mechanism. Several disclosed polyamine-appended materials exhibit strong ability to capture CO2 from various compositions. Increased stability of amines in the framework has been achieved using high molecular weight polyamine molecules that coordinate multiple metal sites in the framework. The preparation of these adsorbents as well as their characterization are provided.

Abstract: Primary, secondary (1º,2º) alkylethylenediamine- and alkylpropylenediamine-appended variants of metal-organic framework are provided for CO2 capture applications. Increasing the size of the alkyl group on the secondary amine enhances the stability to diamine volatilization from the metal sites. Two-step adsorption/desorption profiles are overcome by minimizing steric interactions between adjacent ammonium carbamate chains. For instance, the isoreticularly expanded framework Mg2(dotpdc) (dotpdc4?=4,4?-dioxido-[1,1?:4?,1?-terphenyl]-3,3?-dicarboxylate), yields diamine-appended adsorbents displaying a single CO2 adsorption step. Further, use of the isomeric framework Mg-IRMOF-74-II or Mg2(pc-dobpdc) (pc-dobpdc4?=3,3-dioxidobiphenyl-4,4-dicarboxylate, pc=para-carboxylate) also leads to a single CO2 adsorption step with bulky diamines.

Abstract: Polyamines with lengths carefully tailored to the framework dimensions are appended to metal-organic frameworks such as Mg2(dobpdc) (dobpdc4-=4,4?-dioxidobiphenyl-3,3?-dicarboxylate) with the desired loading of one polyamine per two metal sites. The polyamine-appended materials show step-shaped adsorption and desorption profiles due to a cooperative CO2 adsorption/desorption mechanism. Several disclosed polyamine-appended materials exhibit strong ability to capture CO2 from various compositions. Increased stability of amines in the framework has been achieved using high molecular weight polyamine molecules that coordinate multiple metal sites in the framework. The preparation of these adsorbents as well as their characterization are provided.

Abstract: Primary, secondary (1º,2º) alkylethylenediamine- and alkylpropylenediamine-appended variants of metal-organic framework are provided for CO2 capture applications. Increasing the size of the alkyl group on the secondary amine enhances the stability to diamine volatilization from the metal sites. Two-step adsorption/desorption profiles are overcome by minimizing steric interactions between adjacent ammonium carbamate chains. For instance, the isoreticularly expanded framework Mg2(dotpdc) (dotpdc4?=4,4?-dioxido-[1,1?:4?,1?-terphenyl]-3,3?-dicarboxylate), yields diamine-appended adsorbents displaying a single CO2 adsorption step. Further, use of the isomeric framework Mg-IRMOF-74-II or Mg2(pc-dobpdc) (pc-dobpdc4?=3,3-dioxidobiphenyl-4,4-dicarboxylate, pc=para-carboxylate) also leads to a single CO2 adsorption step with bulky diamines.