| abstract |
A compound is represented by Formula (1): n n n n n n n n n n wherein, each X is independently oxygen, sulfur, or selenium; m is 0 or 1; each n is independently 0 or 1; R 1 -R 3 are each independently, for example, hydrogen or alkyl having 1 to 20 carbons;n nwhereinn (i) in the case of m=0, it is excluded that all of R 1 -R 3 are hydrogen at the same time; (ii) in the case of m=0, n=0 and in the case that m is 0, one of n is 0 and the other is 1, it is excluded that “both of X are sulfur and all R 3 s are the same atoms or groups at the same time”; (iii) in the case of m=0, n=1, it is excluded that all R 3 s are the same atoms or groups at the same time, and at least one of R 3 s is hydrogen. |