Shawn K. Collins’s research while affiliated with Université de Montréal and other places

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Publications (98)


TPDYs: Strained Macrocyclic Diynes for Bioconjugation Processes
  • Article

December 2024

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14 Reads

Chemical Communications

Bernard D'Onofrio

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Corentin Cruché

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Kirsten N Hurdal

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[...]

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Shawn K Collins

A terphenyl diyne (TPDY) macrocycle, 3,5-TPDY, has been developed incorporating a bent 1,3-diyne that is active in SPAAC processes affording atropoisomeric triazole products, as well as cycloadditions with diazoacetates and...


Photocatalysts used to harness lower energy wavelengths for photocatalysis.
[a] Synthesis of ligand and respective absorption spectra and emission spectra. [b] Synthesis of the homoleptic complex and respective absorption spectra and emission spectra. [c] Synthesis of the heteroleptic complex and respective absorption spectra and emission spectra.
Photocatalysis using copper complexes. [a] Evaluation in the dimerization of benzylic amines. Light penetration tests. Yields determined by ¹H NMR. [b] X‐crystallographic analysis of [Cu(bathocupSani)2]BF4. Atoms represented as ellipsoids. Hydrogens omitted for clarity. Carbons for each bathocupSani ligand shown in different shades of grey for clarity. Carbon=grey. Oxygen=red.Copper=bronze. Nitrogen=purple. Boron=pink. Fluorine=bright green. Calculated HOMO and LUMO of [Cu(bathocupSani)2]BF4. The ground state optimization and energy calculations were carried out using the B3PW91 functional with dgdzvp as basis set. Excited state calculations were performed using B3LYP as functional with 6–31 g as basis set with acetonitrile as continuous solvent model. (Isovalue=0.03). Schematic of excitation and formation of the triplet charge–separated state using ligand emission energy in homoleptic complex Cu(bathocupSani)2BF4.
Score of the reactivity for amine dimerization and other oxidation processes (yields determined by ¹H NMR and/or chromatography).
Tuning Co‐Operative Energy Transfer in Copper(I) Complexes Using Two‐Photon Absorbing Diimine‐Based Ligand Sensitizers
  • Article
  • Full-text available

October 2024

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12 Reads

Photocatalysis mediated by low energy light wavelengths has potential to enable safer, sustainable synthetic methods. A phenanthroline‐derived ligand bathocupSani, with a large two‐photon absorption (TPA) cross section was used to construct a heteroleptic complex [Cu(bathocupSani)(DPEPhos)]BF4 and a homoleptic complex [Cu(bathocupSani)2]BF4. The ligand and the respective homoleptic complex with copper exhibit two‐photon upconversion with an anti‐Stokes shift of 1.2 eV using red light. The complex [Cu(bathocupSani)2]BF4 promoted energy transfer photocatalysis enabling oxidative dimerization of benzylic amines, sulfide oxidation, phosphine oxidation, boronic acid oxidation and atom‐transfer radical addition.

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Tuning Co‐Operative Energy Transfer in Copper(I) Complexes Using Two‐Photon Absorbing Diimine‐Based Ligand Sensitizers

September 2024

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10 Reads

Angewandte Chemie

Photocatalysis mediated by low energy light wavelengths has potential to enable safer, sustainable synthetic methods. A phenanthroline‐derived ligand bathocupSani, with a large two‐photon absorption (TPA) cross section was used to construct a heteroleptic complex [Cu(bathocupSani)(DPEPhos)]BF4 and a homoleptic complex [Cu(bathocupSani)2]BF4. The ligand and the respective homoleptic complex with copper exhibit two‐photon upconversion with an anti‐Stokes shift of 1.2 eV using red light. The complex [Cu(bathocupSani)2]BF4 promoted energy transfer photocatalysis enabling oxidative dimerization of benzylic amines, sulfide oxidation, phosphine oxidation, boronic acid oxidation and atom‐transfer radical addition.









Citations (63)


... More recently, Collins extended the macrolactonization process to access cyclophanes bearing a chiral ansa chain by merging transition metal (TM) catalysis with biocatalysis ( Fig. 1D). 47 Although this strategy does not achieve planar-chiral control, the dual-catalysis protocol offers a potential solution to address the assembly of planar and central chiralities in a single step. ...

Reference:

Conformationally Defined Planar-Chiral [n]Paracyclophanes Stabilized by Chiral Ansa Chains
Chemoenzymatic synthesis of macrocycles via dynamic kinetic resolution of secondary alcohols
  • Citing Article
  • July 2024

Nature Synthesis

... [19] Recently, a photo-enzymatic DKR of secondary alcohols employing Candida antarctica lipase B (CAL-B) and Cu(dtbbpy)(DPEPhos)BF 4 coupled with disulfide (Ph 3 SiS) 2 was reported, requiring a stoichiometric amount of 1,4-diazabicyclo[2.2.2]octane (DABCO), again in an organic solvent. [20] On the other hand, DKR strategies for acylating secalcohols employing enzymes for both the racemization and acylation steps have been reported scarcely and required organic phases due to the enzyme used for the acylation step. [21] In turn, alcohol dehydrogenases (ADHs) used for the racemization of sec-alcohols require an aqueous environment. ...

Chemoenzymatic Dynamic Kinetic Resolution of Secondary Alcohols and Amines Employing Copper-Based Photocatalysis
  • Citing Article
  • June 2023

ACS Catalysis

... 829 A series of heteroleptic diimine-Binap copper(I) complexes [Cu(NN)(PP 41 )]BF 4 with π-extended diimine ligands including dpq (bis(desmethyl) analogue of ddpq NN 195 ), dppz (NN 197 ) and bdppz (bis(desmethyl) analogue of NN 251 ) were synthesized and characterized. 830 They were shown to display acceptable levels of activity for the reductive debromination of an alkyl bromide but negligible activity in PCET or ET processes. The influence of the incorporation of a naphthalimide unit to the diimine ligand in [Cu(phen)-(Xantphos)]PF 6 ([Cu(NN 1 )(PP 4 )]PF 6 ) was reported and revealed the importance of the way this unit is incorporated (covalently linked or fused). ...

Heteroleptic Copper(I)-Based Complexes Incorporating BINAP and π-Extended Diimines: Synthesis, Catalysis and Biological Applications

Molecules

... [15] As the large-scale synthesis of 2,3-D-A-norbornadienes through a Diels-Alder reaction in flow is established, [14] a current challenge is thus to develop efficient, scalable, and as sustainable as possible chemistry routes for the required dienophile precursors, such as propynenitriles. These valuable molecules can be prepared from their corresponding acetophenones, [16] derivatives that can also be obtained from bio-based renewable sources such as lignin, [17][18][19] thus comply-ing with principle 7 of the "Green ChemisTREE". [20] Alternative synthetic approaches towards propynenitriles include the introduction of the nitrile group in terminal acetylenes, [21][22][23][24] the conversion of other functional groups (e. g. ...

Decomposition of Lignin Models Enabled by Copper-Based Photocatalysis Under Biphasic Conditions
  • Citing Article
  • May 2022

Green Chemistry

... 16,32,72 On the other hand, the photocatalytic isomerization of (E)-to (Z)stilbene was selected as second model reaction. 13,30,73 In all photocatalytic measurements, light > 400 nm was used to prove that visible light is sufficient to enable the efficient use of Al(III) PSs. ...

Heteroleptic Copper-Based Complexes for Energy-Transfer Processes: E → Z Isomerization and Tandem Photocatalytic Sequences
  • Citing Article
  • July 2021

ACS Catalysis

... Vor diesem Hintergrund ist es wichtig, Flow Chemistry auch in die Lehre zu integrieren (Blanco-Ania & Rutjes, 2017). Im Sinne der curricularen Innovationsforschung soll sich Lehre mit aktuellen, relevanten Forschungsthemen und -erkenntnissen mitentwickeln (Tausch, 2004), um die Fähigkeiten der Studierenden im Hinblick auf ihre berufliche Zukunft als Chemiker:innen zu fördern (Kairouz, Charette & Collins, 2021). So empfehlen Blanco-Ania & Rutjes (2017) die Implementierung von Flow Chemistry-Elementen an Hochschulen bereits im frühen Stadium des Bachelorstudiums, da hier Studierende ihre ersten Laborpraktika absolvieren und Elemente der Flow Chemistry bereits an dieser Stelle in die Lehre eingebettet werden sollten. ...

Implementing flow chemistry in education: the NSERC CREATE program in continuous flow science
  • Citing Article
  • January 2021

Journal of Flow Chemistry

... [46] However, the efficient preparation of SeMCs remains a severe challenge because of the limited selenylation methods, [47] especially for the underexplored selenylalkyne containing macrocycles because the intramolecular C(sp)-Se bond formation reaction suitable for constructing macrocycles has not been reported yet. Generally, the synthesis of selenylalkyne containing macrocycles is more challenging than ordinary macrocyclization as there are four consecutive atoms (SeÀ C�CÀ C) arranged in a linear geometry [48] (verified by the crystal structure of SeMC-13, Figure 3), which resulted in stronger ring tension and higher entropic penalty [49] involved in the ring-closing process. Encouraged by the excellent performance of this SeNEx chemistry in intermolecular reactions, we next tested the feasibility of this reaction in SeMCs synthesis. ...

Synthesis and Diversification of Macrocyclic Alkynediyl Sulfide Peptides

... In 2020, Collins reported a general Cu-catalyzed cross-coupling between bromoalkynes and thiols to construct C(sp)À S bond. [38] After examining the reaction carefully, the optimized conditions were obtained as following: a mixture of bromoalkynes 2 (0.24 mmol), thiols 1 (0.26 mmol), Cu(MeCN) 4 PF 6 (0.024 mmol), dtbbpy (0.048 mmol) and 2,6-lutidine (0.48 mmol) in MeCN at rt for 10 min. This Cu-catalyzed cross-coupling was highly tolerant with a wide scope of functionalities. ...

General Cu-Catalyzed C sp –S Coupling
  • Citing Article
  • July 2020

Organic Letters

... On the other hand, organosulfur compounds have long been considered a poison for several transition metal catalysts, which may also have contributed to slowing the adoption of these compounds especially in the field of organometallic synthetic chemistry. However, in recent years, due to the growing interest in sulfur-containing molecules in the pharmaceutical or materials chemistry fields, [2] the chemistry of alkynyl sulfides has shown significant progress, whether for their synthesis [3] or for their applications. [4] They were used in particular as substrates of choice for various mono or difunctionalization reactions such as carbo-or hydrometallation, [5] or hydroelementation, [6] giving access stereo and regioselectively to functionalized tri-or tetrasubstituted alkenyl sulfides. ...

A Synthetic Guide to Alkynyl Sulfides
  • Citing Article
  • June 2020

Organic & Biomolecular Chemistry

... Sterically hindered diimines with 2,9-substituted phenanthrolines are, however, required to further increase the emission intensities and lifetimes, as seen for example with [Cu(dmp)-(DPEphos)] + ([Cu(NN 2 )(PP 1 )] + , entry 20 in Table 3), emitting at 570 nm with a lifetime of 14.3 μs in deaerated dichloromethane. 41 Temperature-dependent measurements of the luminescence of these complexes have, moreover, shown that both the S 1 and T 1 excited states are involved in the emission properties of the heteroleptic [Cu(NN)(PP)] + complexes. At room temperature, most of these complexes show TADF, and depending on the ΔE S-T gap, TADF can be turned off at different temperatures. ...

Evaluating heteroleptic copper(I)-based complexes bearing π -extended diimines in different photocatalytic processes