| 1. |
- Lungerich, Dominik, et al.
(författare)
-
A Singular Molecule-to-Molecule Transformation on Video: The Bottom-Up Synthesis of Fullerene C-60 from Truxene Derivative C60H30
- 2021
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 15:8, s. 12804-12814
-
Tidskriftsartikel (refereegranskat)abstract
- Singular reaction events of small molecules and their dynamics remain a hardly understood territory in chemical sciences since spectroscopy relies on ensemble-averaged data, and microscopic scanning probe techniques show snapshots of frozen scenes. Herein, we report on continuous high-resolution transmission electron microscopic video imaging of the electron-beam-induced bottom-up synthesis of fullerene C-60 through cyclodehydrogenation of tailor-made truxene derivative 1 (C60H30), which was deposited on graphene as substrate. During the reaction, C60H30 transformed in a multistep process to fullerene C-60. Hereby, the precursor, metastable intermediates, and the product were identified by correlations with electron dose-corrected molecular simulations and single-molecule statistical analysis, which were substantiated with extensive density functional theory calculations. Our observations revealed that the initial cyclodehydrogenation pathway leads to thermodynamically favored intermediates through seemingly classical organic reaction mechanisms. However, dynamic interactions of the intermediates with the substrate render graphene as a non-innocent participant in the dehydrogenation process, which leads to a deviation from the classical reaction pathway. Our precise visual comprehension of the dynamic transformation implies that the outcome of electron-beam-initiated reactions can be controlled with careful molecular precursor design, which is important for the development and design of materials by electron beam lithography.
|
|
| 2. |
- Orrego Hernandez, Jessica, 1987, et al.
(författare)
-
Scalable Synthesis of Norbornadienes via in situ Cracking of Dicyclopentadiene Using Continuous Flow Chemistry
- 2021
-
Ingår i: European Journal of Organic Chemistry. - : Wiley. - 1099-0690 .- 1434-193X. ; 2021:38, s. 5337-5342
-
Tidskriftsartikel (refereegranskat)abstract
- The norbornadiene (NBD)-quadricyclane (QC) photoswitch has recently attracted attention due to its use in molecular solar thermal energy systems (MOST). Normally for device testing, several grams are needed. One way of synthesizing NBDs efficiently is through the Diels-Alder reaction between alkynes and cyclopentadiene. However, scaling up the reaction can be troublesome in a research lab environment. Also, dicyclopentadiene needs cracking before utilization which is a time-consuming step. Here, we developed a method where we both scale up the synthesis in a single reaction step that involves both in situ cracking of dicyclopentadiene and the direct reaction of cyclopentadiene with acetylene derivatives using a tubular coiled stainless steel flow reactor. As a proof-of-concept, we synthesized six different NBD compounds and scaled the synthesis to produce 87 g of a novel NBD in 9 h. The NBD is further characterized, showing promising properties for MOST applications. Our new method shows that flow chemistry is an attractive technique for the fast and efficient synthesis of large quantities of NBDs, needed to develop future real-life devices and applications.
|
|
