Noteworthy, locking the hyperpolarized SO with radio-frequency (RF) fields in resonance with the both 1 H and N nuclei extends its lifetime to 1500 s, which greatly exceed magnetization T1 of N nuclei at high (around 10 s) and low (around 200 s) magnetic fields. The proposed photo-SABRE approach opens new possibilities for the hyperpolarization of photoswitchable compounds incorporating azobenzene moiety. Moreover, this technique has the potential of becoming a valuable analytical tool, as methods based on parahydrogen polarization are often inexpensive and easier to implement than other methods of nuclear spin hyperpolarization. The basic idea behind the diversity of parahydrogen induced polarization (PHIP) techniques is to transform the non-equilibrium singlet spin order of pH2 molecule into the observable magnetization of the substrate. The most straightforward approach of hydrogenative PHIP exploits catalytical pairwise hydrogenation of the unsaturated C-C bond of the substrate with pH2. This method provides strong signal enhancement and facile removal of the toxic hydrogenation catalyst. However, it has two major drawbacks, namely, chemical modification of the substrate, which complicates continuous, repetitive experiments, and small variety of biologically relative compounds obtainable as products of hydrogenation. SABRE method addresses both of these issues, allowing hyperpolarizing a broad range of molecular agents in a repetitive manner. This becomes possible due to the reversible coordination of the parahydrogen and the substrate on a special organometallic catalyst, where polarization transfer between pH2 and the substrate occurs via network of nuclear scalar couplings. A conventional SABRE experiment includes bubbling the sample containing the substrate and the catalyst with pH2, while ensuring the conditions for efficient polarization transfer in the SABRE complex. A favorable approach of doing the later relies on coherent spin-mixing at energy level anti-crossing at low and ultra-low magnetic fields. For the case of protons, a stray field of the spectrometer superconducting magnet usually provides the appropriate conditions of millitesla field for polarization transfer. However, to hyperpolarize C or N nuclei (which is a common aim in PHIP experiments) one needs to reduce the magnetic field to around one microTesla and below, which requires using special magnetic shield. Although, from the above consideration it follows that SABRE is feasible only with substrates, which directly coordinate with the SABRE catalyst, there are actually methods to broaden the range of substrates amenable to SABRE approach. Thus, SABRE-Relay method exploits some molecule undergoing chemical exchange with both the SABRE catalyst and the substrate to act as the mediator for polarization transfer. However, this does not work for trans-ABZ, as it does not participate in chemical exchange suitable for SABRE-Relay technique. Instead, we propose to utilize a well-known property of ABZ to undergo trans-cis photo-induced isomerization. Notably, in 2015, Mewis and co-workers attempted to affect the catalytic system of SABRE by light aiming to release the chelating agent dipyridyl from the coordination sphere of iridium hydride, to reactivate the catalyst. They concluded that UV light had no effect. Previously, our experiments revealed that cis-ABZ successfully coordinates with SABRE complex and receives hyperpolarization from pH2 in the form of both net magnetization of 15 N nuclei and singlet order. However, as a stable conformation at room temperature is trans-ABZ, to perform SABRE experiments with cis-ABZ one first has to create it by exposing the trans-ABZ to light. In the absence of light, the back conversion of cis form into trans is relatively slow, which allows to perform SABRE with cis-ABZ on the same sample for several hours. In such experiments, trans-ABZ does not gain any hyperpolarization and we observed only enhanced signals of cis-ABZ. In turn, our approach of simultaneous parahydrogen bubbling and light irradiation leads to efficient polarization transfer to trans-ABZ. In that case, there are three synchronous processes, namely, cis-ABZ exchange with SABRE-complex, trans-cis and cis-trans photoinduced conversion (Scheme. 1). Thus, non-equilibrium parahydrogen polarization is first transferred into the polarization of cis-ABZ, which afterwards switches into trans-ABZ. It is crucial, that trans-ABZ also undergoes photoisomerization, which provides the pool of cis-ABZ, ready to be polarized at the SABRE-complex. Noteworthy, stationary ratio of cis-to trans-ABZ depends on wavelength. As a result, the favorable interplay of all these processes leads to the efficient accumulation of polarization on both cis-and trans-ABZ. Importantly, this technique allows for many repetitions of the hyperpolarization process with the same target molecules since all the chemical processes are cyclic. Each photo-SABRE experiment included the procedure of polarization transfer at ultra-low field (ULF) in the presence of blue light (Fig. .A). The experimental protocol starts from the relaxation delay at high 𝐵 ! field to let the nuclear spins in the sample to reach thermal equilibrium before the experiment. Subsequently, the sample is transferred into the magnetic shield during delay 𝜏 "# = 0.4 𝑠. At that instant of time, the magnetic field inside the shield is set to 𝐵 $ = 50 𝜇𝑇. Then we instantly drop the magnetic field down to 𝐵 %&' which is around one microtesla and apply light irradiation simultaneously with pH2 bubbling for time 𝜏 %&' = 200 𝑠. This induces the transfer of pH2 hyperpolarization to cis-and trans-ABZ. To detect the resulting ABZ polarization, we instantly increase the field back to 𝐵 $ and then shuttle the sample to the 𝐵 ! field of the detection zone. We set the 𝐵 $ field much higher than ULF fields where polarization transfer occurs, which ensures that the nuclear spins in the sample leave ULF field in a non-adiabatic fashion. This elevates the reproducibility of the experiments and simplifies their interpretation. For the detailed description of experimental parameters optimization (including the 𝜏 %&' , the sample temperature and light irradiation properties) see SI.