Controlling the White-Light Generation of [(RSn)4 E6 ]: Effects of Substituent and Chalcogenide Variation.

Eike Dornsiepen,Sangam Chatterjee,Stefanie Dehnen,Florian Dobener

doi:10.1002/anie.201909981

Eike Dornsiepen, Sangam Chatterjee + Show 2 more

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https://doi.org/10.1002/anie.201909981

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Abstract

Adamantane‐type organotin chalcogenide clusters of the general composition [(RT)4S6] (R=aromatic substituent, T=Si, Ge, Sn) have extreme non‐linear optical properties that lead to highly directional white‐light generation (WLG) upon irradiation with an IR laser diode. However, the mechanism is not yet understood. Now, a series of compounds [(RSn)4E6] (R=phenyl, cyclopentadienyl, cyclohexyl, benzyl, CH2CH2(C6H4)CO2Et; E=S, Se), were prepared, characterized, and investigated for their nonlinear optical properties. With the exception of crystalline [(BnSn)4S6], all these compounds exhibit WLG with similar emission spectra; slight blue‐shifts are observed by introduction of cyclopentadienyl substituents, while the introduction of Se in the inorganic core can provoke a red‐shift. These investigations disprove the initial assumption of an aromatic substituent being a necessary precondition; the precondition seems to be the presence of (cyclic) substituents providing enough electron density.

Highlights

Organo Group 14 chalcogenide clusters are organic/ inorganic hybrid compounds consisting of an inorganic cage, which are derived from chalcogenido Group 14 anions[1,2] that feature an organic substituent shell attached to the core by covalent Group 14 element–carbon bonds
In the context of our investigation of functionalized organo Group 14 chalcogenide clusters,[8,9,10,11,12] we have recently found an unprecedented, extreme non-linear optical behavior of the styryl-decorated cluster [(StySn)4S6] (Sty = 4-vinylphenyl),[13] which belongs to the family of organo Group 14 sesquichalcogenide clusters of the general formula [(RT)4E6] (R = organic substituent; T = Si, Ge, Sn; E = O, S, Se, Te).[14,15,16,17,18] [(StySn)4S6] has been obtained as an amorphous powder, but Density functional theory (DFT) calculations reveal that the adamantanetype structure are favored over the double-decker-type isomer by ca. 30 kJ molÀ1
While compounds that lack inversion symmetry are widely known for second-harmonic generation (SHG), we observed white-light generation (WLG) upon irradiation with a commercially available continuous wave (CW) near-infrared laser diode.[13]

Summary

Introduction

Organo Group 14 chalcogenide clusters are organic/ inorganic hybrid compounds consisting of an inorganic cage, which are derived from chalcogenido Group 14 anions[1,2] that feature an organic substituent shell attached to the core by covalent Group 14 element–carbon bonds. We have prepared a range of adamantanetype clusters with different organic substituents and Group 14 elements: [(PhSn)4S6] and [(PhGe)4S6] exhibit WLG, while [(PhSi)4S6], [(MeSn)4S6] and [(NpSn)4S6] do not emit white light; yet, these compounds still show non-linear optical properties by strong SHG instead.[19] For [(PhSi)4S6], this is attributed to the crystallinity of the compound, which suppresses WLG. We intend to further narrow down the chemical and electronic pre-conditions for WLG and have designed a new series of compounds that have cyclic substituents R, including non-aromatic ones. To gain further insight into the role of the cluster cores composition, the series of compounds is realized for both E = sulfur and selenium, with the latter being the first selenide clusters of this kind to be examined for non-linear optical properties. The emission spectra of the amorphous compounds 1 and 4–9 are shown

Results and Discussion

Conclusion

Conflict of interest