Synthetic Nanoarchitectonics of Functional Organic–Inorganic 2D Germanane Heterostructures via Click Chemistry

Abstract

counterparts, resulting in outstanding physicochemical characteristics.Concretely, germanene (the germanium analog of mainstream graphene) and its saturated forms-obtained by topochemical deintercalation of bulkier Ca 2 Ge into 2D germanane (2D-Ge) derivatives where each Ge atom is covalently bonded to a terminal ligand (e.g., H, CH 3 , or CH 2 CHCH 2 )-have recently attracted particular attention since they exhibit similar promising electronic features to graphene. [15][16][17] In addition, the fact that its bandgap can be easily modulated by tailoring the tethered terminal ligand has further stimulated interest in the synthesis of 2D-Ge derivatives, which present themselves as ideal candidates for a variety of (opto)electronic tasks, including bio-sensing, energy storage and conversion, catalysis, and beyond. [4,[18][19][20][21] Albeit being a very promising material, the vast majority of works involving 2D-Ge derivatives are mainly focused on either developing computational studies or discussing fundamental aspects, with minimum emphasis on their experimental implementation. [21,22] Consequently, there is enough room for realizing functional 2D-Ge-based materials/devices and their exploration for specific achievements.To date, the combination of organic and inorganic nanomaterials has led to the creation of unique heterostructuresreferred to as architectures composed of more than one Succeeding graphene, 2D inorganic materials made of reactive van der Waals layers, like 2D germanane (2D-Ge) derivatives, have attracted great attention because their physicochemical characteristics can be entirely tuned by modulating the nature of the surface substituent. Although very interesting from a scientific point of view, almost all the reported works involving 2D-Ge derivatives are focused on computational studies. Herein, a first prototype of organic-inorganic 2D-Ge heterostructure has been synthesized by covalently anchoring thiol-rich carbon dots (CD-SH) onto 2D allyl germanane (2D-aGe) via a simple and green "one-pot" click chemistry approach. Remarkably, the implanted characteristics of the carbon nanomaterial provide new physicochemical features to the resulting 0D/2D heterostructure, making possible its implementation in yet unexplored optoelectronic tasks-e.g., as a fluorescence resonance energy transfer (FRET) sensing system triggered by supramolecular π-π interactions-that are inaccessible for the pristine 2D-aGe counterpart. Consequently, this work builds a foundation toward the robust achievement of functional organic-inorganic 2D-Ge nanoarchitectonics through covalently assembling thiol-rich carbon nanoallotropes on commercially available 2D-aGe.

2D Functionalized Germananes: Synthesis and Applications

“…Muñoz et al [158] 6 Genosensor-Detection of single nucleotide polymorphism GeH; GeMe; 3-cyanopropyl-Ge (GeC 3 CN)…”

“…[157] The fluorescence properties of Ge-allyl were further enhanced by the addition of carbon dots and applied in fluorescence resonance energy transfer (FRET) sensing to monitor carbon nanoparticles in water. [158] For this purpose, thiol-rich carbon dots were covalently anchored on Ge-allyl via thiol-ene click reaction assisted by UV light. The carbon dots-modified Ge-allyl served as a chromophore acceptor to the carbon nanoparticles in water as fluorophore donor.…”

Molecularly “clicking” active moieties to germanium-based inorganic 2D materials

“…As expected, while the Fe 2p and S 2p high-resolution XPS spectra of pristine 2D-aGe just presented a noisy signal, those of functionalized 2D-Ge-Fc were well deconvoluted. In particular, the component from the S 2p contribution centered at 164 eV can be attributed to the C-S binding energy, [29][30][31] which in combination with the additional component fitted at 287.3 eV in the C 1s spectrum (associated to the C-S binding energy), clearly suggests the formation of a new bond between the 2D-aGe and the Fe-SH. Otherwise, the recorded Ge 3d signal recorded for both pristine and functionalized 2D-Ge materials did not reveal significant differences, giving rise to 4 components centered at 25.4 (Ge-Ge), 27.1 (Ge-H), 27.8 (Ge-C) and 28.5 (Ge-O) eV, demonstrating that the material was stable and no oxidization process occurred during the click reaction.…”

“…Nonetheless, click chemistry has recently shown to be a potential method to provide organicinorganic heterostructured 2D-Ge derivatives by simply anchoring thiol-rich carbon nanoallotropes. 31 Consequently, a general synthetic chemical strategy is proposed for expanding the library of 2D-Ge derivatives by covalently assembling active molecular and supramolecular components upon 2D-Ge via click chemistry. For this goal, the reactivity of commercially available allyl 2D-Ge (2D-Ge-CH 2 CHvCH 2 , 2D-aGe) has been exploited for anchoring ad hoc thiol-rich active moieties (R′-SH) through a "one-pot" photoinduced thiol-ene click reaction, resulting in novel 2D-Ge-CH 2 CH 2 CH 2 S-R′ (2D-Ge-R′) derivatives (see Scheme 1 for illustration).…”

“…Nonetheless, click chemistry has recently shown to be a potential method to provide organic-inorganic heterostructured 2D-Ge derivatives by simply anchoring thiol-rich carbon nanoallotropes. 31…”