Topology and ground state control in open-shell donor-acceptor conjugated polymers

Mayer, Kevin S.; Adams, Daniel J.; Eedugurala, Naresh; Paramasivam, Mahalingavelar; Huang, Lifeng; Galuska, Luke; King, Eric R.; Gu, Xiaodan; Bowman, Michael K.; Azoulay, Jason D.

doi:10.1016/j.xcrp.2021.100467

Cited by 22 publications

(39 citation statements)

References 73 publications

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“…For sample moments on the order of 10 –6 emu, as is the case for our samples (Figure c), this downward trend between 300 and 400 K is often observed in the measurement of the sample as well, and the subtraction offsets this trend. Here, the upturn begins around 200 K and is found to be reproducible across sample batches and measurement modes . The upward trend is the clearest in the representation of χ m T versus T shown in Figure a after correcting for the diamagnetic moment.…”

Section: Resultsmentioning

confidence: 57%

“…An often valid assumption in the case of solid materials is the quenching of the orbital moment . EPR studies of P1 give a sharp Lorentzian line shape centered around g = 2.0039 (see Figure a in ref ). The Landé equation gives a g -factor of 2 when L = 0 and J = S , which supports this assumption and allows for the substitution of J = S in the Brillouin function.…”

Section: Resultsmentioning

confidence: 99%

“…As depicted in Figure a, P1 shows a high-spin ground state with Δ E ST = 7.10 × 10 –3 kcal mol –1 , while P2 shows a low-spin ground state with Δ E ST = −5.24 kcal mol –1 . In these materials, this atom-specific substitution modulates the local aromatic character within the donor, which upon extension of the π-system gives rise to dramatic differences in structural, chemical, electronic, and spin-pairing properties of the polymers Figure c,d shows the spin-density distribution of n = 8 oligomers modeled using density functional theory calculations at the unrestricted (U)B3LYP/6-31G** level of theory for P1 and P2 , respectively. , For the singlet diradical, there is significant overlap between α- and β-SOMOs, whereas the triplet minimizes the overlap, with spins occupying separate spaces.…”

Section: Introductionmentioning

confidence: 99%

“…An antiparallel (or antiferromagnetic) alignment of spins ( S = 0, low spin) describes an open-shell singlet, and a parallel (or ferromagnetic) alignment of spins ( S = 1, high spin) describes a triplet. Significant SOMO overlap stabilizes the singlet as the antiparallel spin alignment allows the electrons to occupy the same region of the chain. ,, However, as the bandgap is further narrowed and SOMO orthogonality increases, the triplet can drop in energy to become the ground state.…”

Section: Introductionmentioning

confidence: 99%

“…These DA CPs are composed of the same solubilizing thiadiazoloquinoxaline acceptor with ancillary hexadecylthiophene (−C 16 H 33 ) substituents and 4,4-dimethyl-4 H -cyclopenta[2,1- b :3,4- b’ ]dithiophene (Figure a) or dithieno[3,2- b :2 ′ ,3 ′ - d ]thiophene donors (Figure b). Substitution of C(CH 3 ) 2 at the donor bridgehead position with a S atom provides a means of controlling the bandgap and ground-state spin multiplicity . As depicted in Figure a, P1 shows a high-spin ground state with Δ E ST = 7.10 × 10 –3 kcal mol –1 , while P2 shows a low-spin ground state with Δ E ST = −5.24 kcal mol –1 .…”

Section: Introductionmentioning

confidence: 99%

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Magnetic Characterization of Open-Shell Donor–Acceptor Conjugated Polymers

et al. 2022

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Donor–acceptor (DA) conjugated polymers (CPs) with narrow bandgaps and open-shell electronic structures offer a fundamentally new paradigm for integrating the spin degree of freedom within emerging functional devices. Recent advancements have demonstrated that control of long-range electronic correlations enables low-spin (S = 0) and high-spin (S = 1) DA CPs, in which extended π-conjugation overcomes the intrinsic instability of these electronic configurations in light-element materials. While design strategies that articulate mechanisms of spin alignment, topology control, and quantum mechanical exchange are emerging, dedicated studies of the magnetic behavior of these materials remain rare. Here, we utilize sensitive magnetometry techniques to analyze the magnetic properties of open-shell DA CPs with low- and high-spin ground states. We demonstrate improved measurement accuracy through combining vibrating sample magnetometry and superconducting quantum interference device magnetometry. This serves to overcome challenges associated with the inherently weak magnetic moments of these materials and a measurement environment in which the background signal is always significant and must be carefully removed. Analyzing the results following established models for paramagnetic materials enables precise quantification of the spin quantum number and temperature-dependent spin alignment. These studies articulate approaches that enable precise characterization of the bulk magnetic features of these heterogeneous and disordered materials systems, providing a path for rational property elucidation that will enable the integration of these materials within emerging technologies.

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Section: Resultsmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnetic Characterization of Open-Shell Donor–Acceptor Conjugated Polymers

et al. 2022

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Control of Microporous Structure in Conjugated Microporous Polymer Membranes for Post‐Combustion Carbon Capture

Jia,

Lu,

Yang

et al. 2024

Adv Funct Materials

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Membranes offer a potentially energy‐efficient and space‐saving solution to reduce CO2 emissions and combat global warming. However, engineering membranes with advanced materials for high permeance and reasonable selectivity is a pressing need. In this context, a series of carbazole‐based conjugated microporous polymer (CMP) membranes are fabricated with thicknesses of a few hundred nanometers through in situ electropolymerization for post‐combustion carbon capture. The findings reveal that various experimental conditions, including the monomer concentration, electric potential, and cyclic voltammetry (CV) cycling number, largely impact the polymerization degree of the carbazole‐based CMP, thus influencing the mode of polymer chain packing. An optimal polymerization degree leads to a larger micropore size and a higher fractional free volume (FFV), thus allowing fast CO2 transport. The study first demonstrates the feasibility of using CMPs to fabricate thin film composite (TFC) membranes for post‐combustion carbon capture and confirms the high controllability of their micropores. These insights provide instructive guidance for the future advancement of CMP applications in membrane fabrication for gas separation and other fields that require precise micropore generation and design.

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Magnetic Ordering in a High‐Spin Donor–Acceptor Conjugated Polymer

et al. 2022

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The development of open‐shell organic molecules that magnetically order at room temperature,which can be practically applied, remains a grand challenge in chemistry, physics, and materials science. Despite the exploration of vast chemical space, design paradigms for organic paramagnetic centers generally result in unpaired electron spins that are unstable or isotropic. Here, a high‐spin conjugated polymer is demonstrated, which is composed of alternating cyclopentadithiophene and benzo[1,2‐c;4,5‐c′]bis[1,2,5]thiadiazole heterocycles, in which macromolecular structure and topology coalesce to promote the spin center generation and intermolecular exchange coupling. Electron paramagnetic resonance (EPR) spectroscopy is consistent with spatially localized spins, while magnetic susceptibility measurements show clear anisotropic spin ordering and exchange interactions that persist at room temperature. The application of long‐range π‐correlations for spin center generation promotes remarkable stability. This work offers a fundamentally new approach to the implementation of this long‐sought‐after physical phenomenon within organic materials and the integration of manifold properties within emerging technologies.

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Topology and ground state control in open-shell donor-acceptor conjugated polymers

Cited by 22 publications

References 73 publications

Magnetic Characterization of Open-Shell Donor–Acceptor Conjugated Polymers

Magnetic Characterization of Open-Shell Donor–Acceptor Conjugated Polymers

Control of Microporous Structure in Conjugated Microporous Polymer Membranes for Post‐Combustion Carbon Capture

Magnetic Ordering in a High‐Spin Donor–Acceptor Conjugated Polymer

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