Stable luminescent azaboraacenium ions

A compound of formula (I-a), (I-b), or (I-c),

• wherein
• L is N-heterocyclic carbene (NHC) or a carbone having a structure of
• wherein each of L1 and L2 is independently a Lewis base;
• G is a heteroaryl or heterocyclyl, which is optionally substituted;
• RA at each occurrence is independently alkyl, alkoxy, haloalkyl, aryl, cyano, halogen, N(RA1)(RA1), S(RB), or thiophenyl;
• RB at each occurrence is independently hydrogen, alkyl, an optionally substituted aryl, or C≡CSi(RB1)3;
• RA1 at each occurrence is independently hydrogen, alkyl, or aryl, or two RA1 together with the nitrogen atom to which they are attached form a ring;
• RB1 at each occurrence is independently alkyl;
• a at each occurrence is independently 0-20;
• m1 is 0-10;
• m2 is 0-10;
• and
• Z is a counterion.