O=C(Cn1c2ccc(Br)cc2c2nc3ccccc3nc21)NNC(=S)NC1CCCCC1
An acid's negative base-10 logarithmic dissociation constant (pKa) follows directly from its underlying thermodynamics; the negative pKa is directly proportional to its standard Gibbs free energy change. What is the negative pKa value of this molecule?