diff --git a/examples/example_p1.json b/examples/example_p1.json
index 1fd33ba..5639a9c 100644
--- a/examples/example_p1.json
+++ b/examples/example_p1.json
@@ -22,17 +22,17 @@
     {
       "relation_type": "IS_PART_OF",
       "related_identifier": "https://example.org/collection",
-      "datetime_log": "2024-02-19T00:00:00Z"
+      "datetime_log": "2024-02-19T00:00:00+00:00"
     },
     {
       "relation_type": "IS_REFERENCED_BY",
       "related_identifier": "https://example.org/referenced",
-      "datetime_log": "2024-02-19T00:00:00Z"
+      "datetime_log": "2024-02-19T00:00:00+00:00"
     }
   ],
   "change_log": [
     {
-      "datetime_log": "2024-02-19T00:00:00Z",
+      "datetime_log": "2024-02-19T00:00:00+00:00",
       "has_agent": {
         "name": "Data Fuzzi",
         "email": "data.fuzzi@example.org",
@@ -44,7 +44,7 @@
       "description": "Registration completed."
     },
     {
-      "datetime_log": "2024-05-15T15:51:15Z",
+      "datetime_log": "2024-05-15T15:51:15+00:00",
       "has_agent": {
         "name": "Data Fuzzi",
         "email": "data.fuzzi@example.org",
diff --git a/examples/example_p1_dataclasses.py b/examples/example_p1_dataclasses.py
index 8207e5e..84f891e 100644
--- a/examples/example_p1_dataclasses.py
+++ b/examples/example_p1_dataclasses.py
@@ -1,8 +1,13 @@
+import sys
+from datetime import datetime
 from linkml_runtime.dumpers import json_dumper
 from pid4cat_model.datamodel import pid4cat_model as p4c
 
 # Demonstrate the use of Python DataClass-based model
 
+if sys.version_info < (3, 11):
+    raise RuntimeError("Python 3.11 or higher is required due to the use of datetime.fromisoformat")
+
 p1_Agent = p4c.Agent(
     name="Data Fuzzi",
     email="data.fuzzi@example.org",
@@ -15,12 +20,12 @@
     p4c.PID4CatRelation(
         relation_type=p4c.RelationType.IS_PART_OF,
         related_identifier="https://example.org/collection",
-        datetime_log="2024-02-19T00:00:00Z",
+        datetime_log=datetime.fromisoformat("2024-02-19T00:00:00Z"),
     ),
     p4c.PID4CatRelation(
         relation_type=p4c.RelationType.IS_REFERENCED_BY,
         related_identifier="https://example.org/referenced",
-        datetime_log="2024-02-19T00:00:00Z",
+        datetime_log=datetime.fromisoformat("2024-02-19T00:00:00Z"),
     ),
 ]
 
@@ -43,13 +48,13 @@
 
 p1_log = [
     p4c.LogRecord(
-        datetime_log="2024-02-19T00:00:00Z",
+        datetime_log=datetime.fromisoformat("2024-02-19T00:00:00Z"),
         has_agent=p1_Agent,
         changed_field=p4c.ChangeLogField.STATUS,
         description="Registration completed.",
     ),
     p4c.LogRecord(
-        datetime_log="2024-05-15T15:51:15Z",
+        datetime_log=datetime.fromisoformat("2024-05-15T15:51:15Z"),
         has_agent=p1_Agent,
         changed_field=p4c.ChangeLogField.RESOURCE_INFO,
         description="as requested in issue #234",
diff --git a/examples/example_p1_pydantic.py b/examples/example_p1_pydantic.py
index cc9fb0d..dcafae9 100644
--- a/examples/example_p1_pydantic.py
+++ b/examples/example_p1_pydantic.py
@@ -1,9 +1,14 @@
+import sys
+from datetime import datetime
 from pathlib import Path
 from linkml_runtime.dumpers import json_dumper, yaml_dumper
 from pid4cat_model.datamodel import pid4cat_model_pydantic as p4c
 
 # Demonstrate the use of Pydantic models
 
+if sys.version_info < (3, 11):
+    raise RuntimeError("Python 3.11 or higher is required due to the use of datetime.fromisoformat")
+
 p1_Agent = p4c.Agent(
     name="Data Fuzzi",
     email="data.fuzzi@example.org",
@@ -16,12 +21,12 @@
     p4c.PID4CatRelation(
         relation_type=p4c.RelationType.IS_PART_OF,
         related_identifier="https://example.org/collection",
-        datetime_log="2024-02-19T00:00:00Z",
+        datetime_log=datetime.fromisoformat("2024-02-19T00:00:00Z"),
     ),
     p4c.PID4CatRelation(
         relation_type=p4c.RelationType.IS_REFERENCED_BY,
         related_identifier="https://example.org/referenced",
-        datetime_log="2024-02-19T00:00:00Z",
+        datetime_log=datetime.fromisoformat("2024-02-19T00:00:00Z"),
     ),
 ]
 
@@ -44,13 +49,13 @@
 
 p1_log = [
     p4c.LogRecord(
-        datetime_log="2024-02-19T00:00:00Z",
+        datetime_log=datetime.fromisoformat("2024-02-19T00:00:00Z"),
         has_agent=p1_Agent,
         changed_field=p4c.ChangeLogField.STATUS,
         description="Registration completed.",
     ),
     p4c.LogRecord(
-        datetime_log="2024-05-15T15:51:15Z",
+        datetime_log=datetime.fromisoformat("2024-05-15T15:51:15Z"),
         has_agent=p1_Agent,
         changed_field=p4c.ChangeLogField.RESOURCE_INFO,
         description="as requested in issue #234",
@@ -73,6 +78,8 @@
 
 print(p1)
 
+print(yaml_dumper.dumps(c))
+
 print(json_dumper.dumps(p1))
 
 # write json to file
@@ -80,5 +87,3 @@
 
 with open(script_folder / "example_p1.json", "w", encoding="utf-8") as f:
     f.write(json_dumper.dumps(p1))
-
-print(yaml_dumper.dumps(c))