Scalable Synthesis of Norbornadienes via in situ Cracking of Dicyclopentadiene Using Continuous Flow Chemistry

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 timeconsuming 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.

High Level Electronic Structure Calculation of Molecular Solid-State NMR Shielding Constants

“…As the size of the QM system in the QM/MM approach can become rather big if one wants to include all the adjacent molecules to the central asymmetric unit, the literature only reports results using (meta-)­GGA or hybrid functionals for the calculation of SCs for SS-NMR. However, double-hybrid functionals such as DSD-PBEP86 or B2PLYP and post-HF methods like MP2 have been shown to lead to a great improvement of accuracy for the calculation of NMR SCs on small molecules, when compared with precise but computationally demanding methods like coupled cluster theory. ,,, Recently, Dračínský et al presented a study on the molecular crystals of six amino acids using MP2 or CCSD corrections on PBE GIPAW results . These corrections were obtained by calculating the isolated single amino acid molecules at a higher level of theory.…”

“…However, double-hybrid functionals such as DSD-PBEP86 or B2PLYP and post-HF methods like MP2 have been shown to lead to a great improvement of accuracy for the calculation of NMR SCs on small molecules, when compared with precise but computationally demanding methods like coupled cluster theory. 15 , 16 , 5 , 17 Recently, Dračínský et al presented a study on the molecular crystals of six amino acids using MP2 or CCSD corrections on PBE GIPAW results. 18 These corrections were obtained by calculating the isolated single amino acid molecules at a higher level of theory.…”

Status and challenges for molecular solar thermal energy storage system based devices

“…Fortunately, improving technology means the cost of large-scale industrial implementation can largely be balanced by the energy saved. In addition, molecular screening by using machine learning and artificial intelligence (AI) technology 49 will also accelerate the discovery of new candidates, and automation of chemistry systems 50 will increase the potential for scaling up. However, unique and niche, small-scale applications, such as wearable MOST cloth or hybrid devices, may be areas where the MOST systems can be applied in a not too distant future.…”

Unveiling the Potential of Heterogeneous Catalysts for Molecular Solar Thermal Systems

“…Known as MOlecular Solar Thermal (MOST) systems, [2][3][4][5] they hold significant potential for revolutionizing the way we generate and store energy. [22][23][24][25] To be used as MOST systems, molecules must possess several key features (Figure 1a). First, they should absorb solar light efficiently, thanks to a good match between the solar spectrum and their absorption spectrum.…”

“…This energy can be released as heat when needed, making these systems ideal for providing energy on demand. Known as MOlecular Solar Thermal (MOST) systems, [2–5] they hold significant potential for revolutionizing the way we generate and store energy [22–25] …”