  Nuclear spin hyperpolarization provides a promising route to overcome the
challenges imposed by the limited sensitivity of nuclear magnetic resonance.
Here we demonstrate that dissolution of spin-polarized pentacene-doped
naphthalene crystals enables transfer of polarization to target molecules via
intermolecular cross relaxation at room temperature and moderate magnetic
fields (1.45$\,$T). This makes it possible to exploit the high spin
polarization of optically polarized crystals while mitigating the challenges of
its transfer to external nuclei, particularly of the large distances and
prohibitively weak coupling between source and target nuclei across solid-solid
or solid-liquid interfaces. With this method, here we inject the highly
polarized mixture into a benchtop NMR spectrometer and observe the polarization
dynamics for target $^1$H nuclei. Although the spectra are radiation damped due
to the high naphthalene magnetization, we describe a procedure to process the
data in order to obtain more conventional NMR spectra, and extract the target
nuclei polarization. With the entire process occurring on a timescale of one
minute, we observe NMR signals enhanced by factors between -200 and -1730 at
1.45$\,$T for a range of small molecules.
