| 主权项 |
1. A compound represented by formula I, Formula I in the formula I, both R1 and R2 are represented as groups shown in the following A, B or C: A. at least one of group selected from H, —Cl, —F, —CN, —OCN, —OCF3, —CF3, —CHF2, —CH2F, —OCHF2, —SCN, —NCS, —SFS, C1-C15 alkyl, C1-C15 alkoxy, C2-C15 alkenyl and C2-C15 alkenoxy; B. groups obtained by substituting one or at least two non-adjacent —CH2— in A groups with at least one of following groups and to which oxygen atoms are not directly attached: —CH═CH—, —CC—, —COO—, —OOC—,cyclobutyl, —O— or —S—; C. at least one of groups obtained by substituting at least one of hydrogen in A groups and B groups with fluorine or chlorine;are at least one of a single bond or following groups: Z1 and Z2 are same or different, both of them are selected from at least one of a single bond, —CH2—, —CH2—CH2—, —(CH2)3—, —(CH2)4—, —CH═CH—, —CC—, —COO—, —OOC—, —CF2O—, —OCH2—, —CH2O—, —OCF2—, —CF2CH2—, —CH2CF2—, —C2F4— and —CF═CF—; a, b and c are an integer from 0 to 3, and a+b+c≦5; when a, b and c represents 2 or 3 respectively, the groups represented bymay be same or different, the groups represented bymay be same or different, and the groups represented bymay be same or different. |
