Robert Pal

Circularly polarised luminescence (CPL) spectroscopy is a technique with applications in materials chemistry, bioimaging, probing fundamental chirality, but conventional photo-elastic modulator CPL instruments remain bulky, expensive and slow. We report a compact single-channel CPL (SC-CPL) spectrometer that alternates left-and righthanded emission through a piezo-actuated pair of orthogonally aligned achromatic quarter-wave plates using a rapid CCD detector. This design minimises moving optics and eliminates the need for detector matching and pre-calibration. It can operate in various acquisition modes such as time gated acquisition mode for long-lived CPL emission and a quasi-continuous mode for short-lived CPL emission. Validation against a benchmark PEM-CPL system using a range of CPL emitters reproduced fine CPL resolution with high sensitivity, orders of magnitude faster. This blueprint SC-CPL reported herein paves the way towards the world's first complete compact chiroptical toolbox. This could lead to significant advancements with pivotal scientific and societal impact.

Circularly polarized luminescence (CPL) imaging of biomolecules using designed chiral probes holds significant promise for biochemical and analytical applications. In this work, we report two chiral hetero[9]helicene multi-resonant thermally activated delayed fluorescent (MR-TADF) organic molecules DDCzBPh and DDCzBPy , consisting of two annulated MR-TADF units to a central naphthyl or quinoxanyl group, respectively, which exhibit simultaneously strong CPL, two-photon absorption, high photoluminescence quantum yields, and long-lived delayed fluorescence. We demonstrate two-photon-excited CPL of TADF emitters, with their circularly polarized brightness of 0.2 GM, demonstrating their potential for CPL biological imaging.

Circularly polarised luminescence (CPL) spectroscopy is a technique with applications in materials chemistry, bioimaging, probing fundamental chirality, but conventional photo-elastic modulator CPL instruments remain bulky, expensive and slow. We report a compact single-channel CPL (SC-CPL) spectrometer that alternates left-and righthanded emission through a piezo-actuated pair of orthogonally aligned achromatic quarter-wave plates using a rapid CCD detector. This design minimises moving optics and eliminates the need for detector matching and pre-calibration. It can operate in various acquisition modes such as time gated acquisition mode for long-lived CPL emission and a quasi-continuous mode for short-lived CPL emission. Validation against a benchmark PEM-CPL system using a range of CPL emitters reproduced fine CPL resolution with high sensitivity, orders of magnitude faster. This blueprint SC-CPL reported herein paves the way towards the world's first complete compact chiroptical toolbox. This could lead to significant advancements with pivotal scientific and societal impact.

A series of novel arylalkynylpyridyl‐triazacyclononane sensitized macrocyclic europium(III) complexes (EuL) was prepared, and their circularly polarized luminescence characterized in terms of the spectral profile and dissymmetry factor ( g _lum ). The series was engineered based on previously reported isostructural complexes by a controlled introduction of structural modifications at different positions with respect to the coordination environment of the emitting europium(III) center. It was established that only those structural features of the macrocyclic ligand that were proximal to the europium(III) center affected CPL properties. These findings could help shape the development of a new class of purpose‐built EuL complexes compatible with CPL‐unaffecting complex‐stage functionalization to introduce advantageous structural features for applications in life and material sciences.

The twisting of chromophores such as perylene diimides (PDIs) into helical structures affords chiroptical properties from discrete molecules, which are of significant value for chiral sensing, imaging and catalysis. Since most helical PDI derivatives are susceptible to racemisation, chiral induction provides a promising, yet underdeveloped, strategy for generating materials with persistent chiroptical properties. For the first time, we use a mechanically planar chiral rotaxane as a configurationally stable chirality source to induce single‐handed helicity in a molecular chromophore, yielding persistent circular dichroism and circularly polarised luminescence. The large π‐surface of the PDI also enables rotaxane self‐assembly, which is rare among mechanically interlocked molecules. While mechanical bonding is shown to influence the geometry of the resulting PDI dimers, mechanical planar chirality directs their handedness, thereby providing control at both the molecular and supramolecular levels.

The twisting of chromophores such as perylene diimides (PDIs) into helical structures affords chiroptical properties from discrete molecules, which are of significant value for chiral sensing, imaging and catalysis. Since most helical PDI derivatives are susceptible to racemisation, chiral induction provides a promising, yet underdeveloped, strategy for generating materials with persistent chiroptical properties. For the first time, we use a mechanically planar chiral rotaxane as a configurationally stable chirality source to induce single‐handed helicity in a molecular chromophore, yielding persistent circular dichroism and circularly polarised luminescence. The large π‐surface of the PDI also enables rotaxane self‐assembly, which is rare among mechanically interlocked molecules. While mechanical bonding is shown to influence the geometry of the resulting PDI dimers, mechanical planar chirality directs their handedness, thereby providing control at both the molecular and supramolecular levels.

Dynamic quenching of the lanthanide excited state is greatest for Tb complexes compared to Eu and reveals selective quenching of the Δ enantiomer by R -Trolox.

Chiral quenching of the Tb and Eu excited state occurs preferentially for the Δ enantiomer by R -Trolox, via exciplex formation.

Life on Earth is predominately based upon a single chirality set, but so-called “mirror life” - speculated life of the opposite chirality, either of artificial or natural origin - presents a low-likelihood, but high severity global biosecurity threat. Such an existential risk necessitates that technologies for surveillance and containment of mirror life are developed as a contingency. In this perspective, we propose a method for screening against mirror life hazards via an optical chirality assay, based upon circularly polarized luminescence (CPL) generated either via achiral fluorophores (via supramolecular chirality effects) or intrinsically chiral molecular probes. When bound to biological molecules, CPL-generating probes enable Enantioselective Differential Chiral Contrast (EDCC) imaging to verify chirality of a biological specimen. We set out why a multi-reporter panel approach – incorporating many CPL generating fluorescent/luminescent complexes – in conjunction with testing on conventional life’s chirality set, would be necessary to avoid false positives, and thereby screen against mirror life with a high degree of confidence. The all-optical approach could be deployed via recently innovated optical technologies, i.e. rapid CPL spectroscopy, CPL EDCC microscopes, and CPL EDCC cameras. We envisage that this CPL-based approach to screening against mirror life could be a useful tool for safeguarding against mirror life biohazards in a complimentary manner to any future legislative controls.

Life on Earth is predominately based upon a single chirality set, but so-called “mirror life” - speculated life of the opposite chirality, either of artificial or natural origin - presents a low-likelihood, but high severity global biosecurity threat. Such an existential risk necessitates that technologies for surveillance and containment of mirror life are developed as a contingency. In this perspective, we propose a method for screening against mirror life hazards via an optical chirality assay, based upon circularly polarized luminescence (CPL) generated either via achiral fluorophores (via supramolecular chirality effects) or intrinsically chiral molecular probes. When bound to biological molecules, CPL-generating probes enable Enantioselective Differential Chiral Contrast (EDCC) imaging to verify chirality of a biological specimen. We set out why a multi-reporter panel approach – incorporating many CPL generating fluorescent/luminescent complexes – in conjunction with testing on conventional life’s chirality set, would be necessary to avoid false positives, and thereby screen against mirror life with a high degree of confidence. The all-optical approach could be deployed via recently innovated optical technologies, i.e. rapid CPL spectroscopy, CPL EDCC microscopes, and CPL EDCC cameras. We envisage that this CPL-based approach to screening against mirror life could be a useful tool for safeguarding against mirror life biohazards in a complimentary manner to any future legislative controls.