  As host to two accreting planets, PDS 70 provides a unique opportunity to
probe the chemical complexity of atmosphere-forming material. We present ALMA
Band 6 observations of the PDS~70 disk and report the first chemical inventory
of the system. With a spatial resolution of 0.4''-0.5'' ($\sim$50 au), 12
species are detected, including CO isotopologues and formaldehyde, small
hydrocarbons, HCN and HCO+ isotopologues, and S-bearing molecules. SO and CH3OH
are not detected. All lines show a large cavity at the center of the disk,
indicative of the deep gap carved by the massive planets. The radial profiles
of the line emission are compared to the (sub-)mm continuum and infrared
scattered light intensity profiles. Different molecular transitions peak at
different radii, revealing the complex interplay between density, temperature
and chemistry in setting molecular abundances. Column densities and optical
depth profiles are derived for all detected molecules, and upper limits
obtained for the non detections. Excitation temperature is obtained for H2CO.
Deuteration and nitrogen fractionation profiles from the hydro-cyanide lines
show radially increasing fractionation levels. Comparison of the disk chemical
inventory to grids of chemical models from the literature strongly suggests a
disk molecular layer hosting a carbon to oxygen ratio C/O>1, thus providing for
the first time compelling evidence of planets actively accreting high C/O ratio
gas at present time.
