Adamantanes as White-Light Emitters: Controlling the Arrangement and Functionality by External Coulomb Forces

Abstract

Functionalized adamantane molecular cluster materials show highly transient nonlinear optical properties of currently unclear structural origin. Several interaction mechanisms in compounds comprising molecular clusters and their inter- and intramolecular interactions as well as the interplay of their electronic systems and vibrations of their backbone are viable concepts to explain these nonlinear optical properties. We show that transient Coulomb forces also have to be considered as they can lead to intramolecular structural transformations and intermolecular rearrangements in the crystal. Both strongly influence the nonlinear optical properties. Moreover, selective bromine functionalization can trigger a photochemical rearrangement of the molecules. The structure and chemical bonding within the compounds are investigated in relation to the laser irradiation at different stages of their nonlinear emission by electron diffraction and electron energy loss spectroscopy. The transient structural and chemical states observed are benchmarked by similar observations during electron irradiation, which makes quantification of structural changes possible and allows the correlation with first-principles calculations. The functionalization and its subsequent usage to exploit photochemical effects can either enhance two-photon absorption or facilitate white-light emission rather than the second-harmonic generation.

Designing Excess Electron Compounds by Substituting Alkali Metals to a Small and Versatile Tetracyclic Framework: A Theoretical Perspective

“…Such a feature has already been found in the instance of adamantane substituted with an alkali metal and Ti@C 28 . It is noted that the intramolecular charge transfer is directly connected to the NLO response of systems. , …”

“… 51 It is noted that the intramolecular charge transfer is directly connected to the NLO response of systems. 52 , 53 …”

“…51 It is noted that the intramolecular charge transfer is directly connected to the NLO response of systems. 52,53 To obtain more insights into the charge transfer and electronic properties, we analyzed FMOs. The transitions in FMOs that are highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) are one of the key factors in determining the optoelectronic properties of any molecule.…”

Adamantane-type clusters: compounds with a ubiquitous architecture but a wide variety of compositions and unexpected materials properties

“…Using a stoichiometric ratio, the formation of coordination polymers has been reported. Reactions with the iron carbonyl [Fe(CO)5] can similarly be carried out, but proceed much slower and at higher temperatures (653)(654)(655)(656). [351,353] [P4S10] (657, Figure 14) is most easily obtained from the elements using method A, though many methods are available.…”

Annulated carbamates are precursors for the ring contraction of the adamantane framework

“…Together with adamantane derivatives, 5 they are typically used to make target molecules more lipophilic, bulky or conformationally rigid, which is exploited in drug 6 and catalyst design 7 or in materials science for preparation of polymers, dendrimers, and light emitting and other special devices. 8 Noradamantane compounds can also serve as precursors for the synthesis of adamantane derivatives via ring expansion methods. 9 Various simple noradamantane derivatives ( e.g.…”