Abstract
Naphthalenediimide derivates are a class of π-conjugated molecules largely investigated in the literature and used as building blocks for metal–organic frameworks or coformers for hydrogen-bond-based cocrystals. However, their tendency to establish halogen-bond interactions remains unexplored. By using a crystalline engineering approach, we report here four new cocrystals with N,N′-di(4-pyrydyl)-naphthalene-1,4,5,8-tetracarboxidiimide and diiodo-substituted coformers, easily obtained via a mechanochemical protocol. Cocrystals were characterized via NMR, electron ionization mass spectrometry, thermogravimetric analysis, powder X-ray diffraction, and single-crystal X-ray diffraction. Crystallographic structures were then finely examined and correlated with energy framework calculations to understand the relative contribution of halogen-bond and π–π interactions toward framework stabilization.
Highlights
Cocrystals are multicomponent compounds made of different chemical entities stoichiometrically interacting within the crystal lattice.[1−4] Cocrystallization alters the physical−chemical properties of the individual molecular components; designing a cocrystal requires a thorough knowledge of the possible intermolecular affinity between the molecular partners, providing a robust intermolecular network.[4]
N,N′-di(4-pyridyl)-naphthalene-1,4,5,8-tetracarboxydiimide (1) belongs to the class of naphthalenediimides (NDI), rigid πconjugated molecules characterized by an electron-poor naphthalene core (Scheme 1) largely investigated in the past decade
Their electron affinity, ability to behave as charge carriers, and excellent thermal and oxidative stability make them promising candidates for organic electronic applications, photovoltaic devices, and flexible displays.[11−15] The robustness of the aromatic core has pushed forward the use of NDIs as rigid linkers for chemoresponsive luminescent metal−organic frameworks (MOFs),[16−22] metallacycles,[23−26] or supramolecular assemblies.[27]
Summary
Cocrystals are multicomponent compounds made of different chemical entities stoichiometrically interacting within the crystal lattice.[1−4] Cocrystallization alters the physical−chemical properties of the individual molecular components; designing a cocrystal requires a thorough knowledge of the possible intermolecular affinity between the molecular partners, providing a robust intermolecular network.[4]. N,N′-di(4-pyridyl)-naphthalene-1,4,5,8-tetracarboxydiimide (1) belongs to the class of naphthalenediimides (NDI), rigid πconjugated molecules characterized by an electron-poor naphthalene core (Scheme 1) largely investigated in the past decade Their electron affinity, ability to behave as charge carriers, and excellent thermal and oxidative stability make them promising candidates for organic electronic applications, photovoltaic devices, and flexible displays.[11−15] The robustness of the aromatic core has pushed forward the use of NDIs as rigid linkers for chemoresponsive luminescent metal−organic frameworks (MOFs),[16−22] metallacycles,[23−26] or supramolecular assemblies.[27] Exploiting their affinity with aromatic guest molecules that influence their emission profile, it is possible to reveal the guest uptake even at very low concentrations.[19] NDIs have been largely investigated as coformers for hydrogen-bond (HB)-based cocrystals.[28] pyridine-based systems have been extensively used for halogen-bond (XB)-based cocrystals,[29] to the best of our knowledge 1 has never been embedded in a cocrystal matrix through a halogen bond connecting the pyridine moieties with XB donors. Owing to the low solubility of 1, cocrystallization reactions conducted in solution led to the Received: May 7, 2021 Revised: July 19, 2021 Published: September 1, 2021
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