Novel Insight into the Molecular Frustration of IFLPs Based on Boron-Functionalized Pyrimidines for CO₂ Sequestration

Abstract

The emergence of frustrated Lewis pairs (FLPs) as organocatalysts for CO 2 sequestration has opened a new dimension in this area. To date, various inter-and intramolecular frustrated Lewis pairs have been experimentally and theoretically explored for CO 2 activation, still there is plenty of room for new insights into FLPs. Thus, in the present study intramolecular frustrated Lewis pairs (IFLPs) based on boron-functionalized pyrimidines have been proposed for CO 2 activation and computationally investigated to gain new insights into the molecular frustration. The extensive natural bond orbital (NBO) analysis unveils an interesting relationship between the orbital charge transfer and the activity. The result shows that the greater the charge transfer between the acidic and basic sites, the higher will be the frustration in the molecule. Also, the presence of atoms bearing a lone pair attached to the acidic site relieves the frustration by charge transfer. Based on the orbital charge transfer, the predicted activity order for the proposed IFLPs is supported by the energetics for the reaction of CO 2 with the IFLPs. Further, the activation strain analysis (ASA) provides a different viewpoint about the reactivities of the IFLPs and highlights the importance of the geometrical structure of the catalyst. Furthermore, the ab initio molecular dynamics (AIMD) uplights the reversibility of the formed products.

Unprecedented Activation of CO2 by α-Amino Boronic Acids

“…The presence of V max above the −B(OH) 2 plane near V min of the N atom indicates the simultaneous existence of the electron-rich and -deficient sites in the molecule as observed in FLPs. 47,55,56 Thus, in the gas phase, AABs may have the catalytic action similar to that of FLPs. In comparison to the gas phase, the MESP in the presence of propanol (Figure 3) shows only the presence of one V max associated with the B atom which is below the −B(OH) 2 plane.…”

“…For example, Stephan and co-workers have successfully demonstrated the room temperature conversion of CO 2 to methanol by Al-based FLP . Since the advent of FLPs, various inter- and intramolecular FLPs have been designed, developed, and investigated experimentally and theoretically for the activation of CO 2 molecules. − …”

PIO and IBO analysis to unravel the hidden details of the CO2 sequestration mechanism of aromatically tempered N/B-based IFLPs

“…32 Since the arrival of FLPs, various inter-and intramolecular FLPs have been developed and investigated for the sequestration of CO 2 molecules. [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] Fig. 1 The general structure of (a) intermolecular FLPs and (b) intramolecular FLPs.…”

Alanine boronic acid functionalized UiO‐66 MOF as a nanoreactor for the conversion of CO2 into formic acid

“…[29][30][31][32] Since the first appearance of FLPs, various FLPs have been developed and investigated for CO 2 sequestration. [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] Recently, Jiang and co-workers investigated Phosphorus/Boron based bridged FLPs for CO 2 hydrogenation and found them to be a potential catalyst. 52 In addition to the molecular catalysts, reactions inside molecular confinements have also been considered as a powerful tool in accelerating the reaction.…”

“…Thus, the quest for developing a better and metal‐free catalyst for CO 2 reduction is going on, 18–28 and the emergence of Frustrated Lewis pairs (FLPs) has created a whole new dimension in this area 29–32 . Since the first appearance of FLPs, various FLPs have been developed and investigated for CO 2 sequestration 33–51 . Recently, Jiang and co‐workers investigated Phosphorus/Boron based bridged FLPs for CO 2 hydrogenation and found them to be a potential catalyst 52 …”