TY - JOUR

T1 - Stacked but not Stuck

T2 - Unveiling the Role of π→π* Interactions with the Help of the Benzofuran–Formaldehyde Complex

AU - Li, Xiaolong

AU - Spada, Lorenzo

AU - Alessandrini, Silvia

AU - Zheng, Yang

AU - Lengsfeld, Kevin Gregor

AU - Grabow, Jens Uwe

AU - Feng, Gang

AU - Puzzarini, Cristina

AU - Barone, Vincenzo

N1 - Funding Information: Financial support from the Italian Ministry of University and Research (Grant Number 2017A4XRCA), the Chongqing University, the Land Niedersachsen, and the Deutsche Forschungsgemeinschaft (DFG) are acknowledged. X. Li thanks the China Scholarships Council (CSC) for support. K. G. Lengsfeld gratefully acknowledges the Fonds der Chemischen Industrie (FCI) for a Ph.D. fellowship. Open Access Funding provided by Scuola Normale Superiore within the CRUI‐CARE Agreement.

PY - 2021/12/27

Y1 - 2021/12/27

N2 - The 1:1 benzofuran–formaldehyde complex has been chosen as model system for analyzing π→π* interactions in supramolecular organizations involving heteroaromatic rings and carbonyl groups. A joint “rotational spectroscopy–quantum chemistry” strategy unveiled the dominant role of π→π* interactions in tuning the intermolecular interactions of such adduct. The exploration of the intermolecular potential energy surface led to the identification of 14 low-energy minima, with 4 stacked isomers being more stable than those linked by hydrogen bond or lone-pair→π interactions. All energy minima are separated by loose transition states, thus suggesting an effective relaxation to the global minimum under the experimental conditions. This expectation has been confirmed by the experimental detection of only one species, which was unambiguously assigned owing to the computation of accurate spectroscopic parameters and the characterization of 11 isotopologues. The large number of isotopic species opened the way to the determination of the first semi-experimental equilibrium structure for a molecular complex of such a dimension.

AB - The 1:1 benzofuran–formaldehyde complex has been chosen as model system for analyzing π→π* interactions in supramolecular organizations involving heteroaromatic rings and carbonyl groups. A joint “rotational spectroscopy–quantum chemistry” strategy unveiled the dominant role of π→π* interactions in tuning the intermolecular interactions of such adduct. The exploration of the intermolecular potential energy surface led to the identification of 14 low-energy minima, with 4 stacked isomers being more stable than those linked by hydrogen bond or lone-pair→π interactions. All energy minima are separated by loose transition states, thus suggesting an effective relaxation to the global minimum under the experimental conditions. This expectation has been confirmed by the experimental detection of only one species, which was unambiguously assigned owing to the computation of accurate spectroscopic parameters and the characterization of 11 isotopologues. The large number of isotopic species opened the way to the determination of the first semi-experimental equilibrium structure for a molecular complex of such a dimension.

KW - bond analysis

KW - non-covalent interaction

KW - quantum chemistry

KW - rotational spectroscopy

KW - structure determination

UR - http://www.scopus.com/inward/record.url?scp=85119669512&partnerID=8YFLogxK

U2 - 10.1002/anie.202113737

DO - 10.1002/anie.202113737

M3 - Article

AN - SCOPUS:85119669512

VL - 61

JO - Angewandte Chemie - International Edition

JF - Angewandte Chemie - International Edition

SN - 1433-7851

IS - 1

M1 - e202113737

ER -